Manual for Refrigeration Servicing Technicians - UNEP - Division of ...

Manual for
Refrigeration
Servicing
Technicians Introduction
Why you need this manual 4
When to use this manual 4
How to use this manual 4
Welcome to the Manual for Refrigeration Servicing Technicians.
It is an e-book for people who are involved in training and
organization of service and maintenance of refrigeration and airconditioning
(RAC) systems. It is aimed at people who are:
• Service and maintenance technicians
• Private company service/maintenance managers
• Private company managers involved in developing their
service and maintenance policy
• Private company technicians trainers
• Educational establishment RAC trainers and course
developers
• National Ozone Units (NOUs) responsible for servicing
and maintenance regulations and programmes related to
the Montreal Protocol.

Introduction
Why you need this Manual
Over recent years, attention on the issue of ozone depletion has
remained focused on the obligatory phasing out of ozone depleting
substances (ODS). At the same time, awareness of climate change
has increased, along with the development of national and regional
greenhouse gas (GHG) emissions reduction targets. In order to
achieve reduction in emissions of both ODSs and GHGs, attention
has to be paid to activities at a micro-level. This includes reducing
leakage rates, improving energy-efficiency and preventing other
environmental impacts, by directing the activities of individuals, and
influencing the design and maintenance of equipment.
The manual is written for those who have a relatively comprehensive
level of knowledge and understanding of RAC systems and
associated technology. The material within this manual may be
used for the purpose of developing training resources or parts
of training courses, as well as general guidance and information
for technicians on issues that are closely related to the use and
application of alternative refrigerants. Most training courses are
likely to cover a range of topics associated with RAC systems, and
as such, the material within this manual may contribute towards
those elements that address refrigerant use and handling.
Read on to find out how 4
2

Introduction
When to use the manual
The overall theme of this manual is to encourage technicians to
work with systems in a more environmentally-friendly manner,
and to get the equipment itself to have a lower impact. However,
the primary motivation for technician operations carried out
on a particular system is typically cost-orientated, rather than
considering the environmental impact. It is often not recognised that
actions resulting in a lesser environmental impact are consistent
with a lower long-term cost impact. Conversely, the types of actions
that are the “cheaper” options tend to lead to greater costs in the
long term, as well as a worse environmental impact.
For example:
• A system that leaks may be topped-up or repaired. Topping-up
may have a lower immediate cost, whereas repairing the leak
takes more time and therefore costs more. However, in the longterm,
the repaired system is less likely to leak thus the costs
cease, whereas repeatedly topping-up a system over months
and years results in a very high accumulated cost. Obviously,
preventing leakage and thus fewer journeys to the equipment
and better resulting efficiency is much more desirable from an
environmental perspective.
• A system that is designed to work efficiently and is well
maintained may cost more to build, but the pay-back period is
generally much shorter than the equipment’s lifetime. Similarly,
the additional GHG emissions associated with constructing
larger heat exchangers (for example) are minute compared to
the reduction in GHG emissions from energy consumption that
will be saved over the first year of operation.
So, when installing a new system or working on an existing system,
the actions taken should ideally lead to the system operating with
minimal impact on the environment. To achieve this, several aspects
should be borne in mind:
• Reduce energy consumption by minimizing heat load and
improving efficiency.
• Minimize leakage and other emissions whenever possible.
• Avoid the use of high global warming potential (GWP)
refrigerants.
Read on to decide how you might use this manual to achieve this 4
3

Introduction
How to use this manual
The objectives on the page 6 When to use this manual may be
achieved through a variety of means, including those detailed within
this manual and from other sources. When a technician arrives at a
system to carry out activities that involve refrigerant handling, and
as they begin their work, they must formulate a view as to how to
deal with the system in hand.
The considerations as to what to do with the system may include:
Repair:
Whether to repair and refill with the same refrigerant.
Drop-in refrigerant change:
Whether to repair and drop-in with a new refrigerant, and if so,
which refrigerant to use.
Retrofitting:
Whether to repair and retrofit with a new refrigerant, and if so, which
refrigerant to use.
Redesign:
Whether to repair, and add refrigerant, but also carry out other
improvements to improve the reliability and efficiency.
Replacement:
Whether to replace the entire system with a new one, and if so,
which system and which refrigerant.
Read The Factors Affecting the Decision 4
4

Introduction
The Factors affecting the decision
The decision as to which approach to take is rarely an obvious one, and
requires consideration of many aspects.
Type of refrigerant and its availability
If a system uses a chlorofluorocarbon (CFC) then it is likely to
be difficult to obtain, or even prohibited. The same will apply to
hydrochlorofluorocarbons (HCFCs) in the future.
Severity of leakage
For systems that have a history of high leakage, perhaps due
to poor manufacture or construction, or being positioned in a
vulnerable location, consideration should be given to replacing
them, or redesigning/reinstalling the susceptible parts.
Charge of refrigerant
If a system has a small charge of controlled or less available
refrigerant, then it may not be so problematic to retain it, whereas if
the charge is large then it would be sensible to replace it.
Availability of alternative refrigerant
The choice of alternative refrigerant should ideally be a substance
with zero ozone depleting potential (ODP) i.e. not a CFC or HCFC or
a blend that contains either. It should have as low a GWP as possible.
Physical size of the system
If a system is very large, replacing it with a new system may require
considerable cost.
Availability of similar (replacement) systems
If the system is particularly complex and a replacement is being
considered, it should only be done provided a replacement system
is easily available.
Availability of expertise associated with the type of
system
Involved types of work or replacing parts or the entire system
should only be done provided that sufficient expertise is available.
Degree of integration into application
Where a system is partially integrated into an application or a
building, or is part of a much larger mechanical installation, it is
likely to be much easier and more cost effective to carry out minimal
work rather than trying to replace it with a new system.
Condition/state of equipment
For systems in a very poor condition, where perpetual maintenance and
repairs are likely, then installation of a new system may be appropriate.
5

Introduction
Age of system
If a system is very old and is using outdated technology and parts,
it could be appropriate to replace it, whereas newer equipment may
have modern design and already use suitable refrigerants.
Current level of reliability
If the reliability of the system and its components are poor, resulting
in repeated service visits and losses of parts and refrigerant, then a
replacement system may be the preferred option.
System efficiency and potential for efficiency
improvement
If a system has a poor level of efficiency, it is necessary to consider
whether there are viable operations that could be carried out to help
improve the efficiency, but it is such that this is not possible, then
adoption of a new system should be considered.
The choice is often complex
and a function of many different
factors. Typically, the age of
the equipment is a leading factor
in terms of which conclusions
are drawn in terms of how the
equipment should be handled,
for the reasons implied above.
6

Introduction
How to assess conditions
Here is an overview of conditions for the refill, drop-in, retro-fit and
new system options, which includes considerations that should be
given to how a system is handled.
Considering these factors, read the conditions below and then select the
option you might choose
The conditions 4
CHAPITRE 1
PAGE 06
HOW TO ASSESS CONDITIONS
FULL INTEGRATED
INTO APPLICATION ?
LIMITED
AVAILABILITY OF
NEW SYSTEMS ?
HCFC , HFC ,
NATURAL
REFRIGERANT ?
LOW LEAKAGE ?
NOT INTEGRATED
INTO APPLICATION ?
EXTENSIVE
AVAILABILITY OF
NEW SYSTEMS ?
HIGH LEAKAGE ?
CFC REFRIGERANT ?
SYSTEM IN GOOD
CONDITION ?
NO EXPERTISE FOR
NEW SYSTEMS ?
SYSTEM IN POOR
CONDITION ?
EXISTING
SYSTEM
EXTENSIVE
EXPERTISE FOR NEW
SYSTEMS ?
NEW
SYSTEM
GOOD RELIABILITY?
GOOD EFFICIENCY ?
POOR RELIABILITY?
POOR EFFICIENCY ?
7
SMALL CHARGE ?
NOT MANY YEARS
OLD ?
GOOD POTENTIAL
FOR EFFICIENCY
IMPROVEMENT ?
LARGE CHARGE ?
MANY YEARS OLD ?
POOR POTENTIAL
FOR EFFICIENCY
IMPROVEMENT ?

Introduction
Refrigerant type and
availability
Condition Observation
HFC, CO2, HC,
NH3
CFC, HCFC HCFC CFC
Severity of leakage low low medium high
Charge of refrigerant high medium medium low
Alternative refrigerant
availability
poor good good good
Physical size of system large large medium small
Availability of similar systems none none none many
Availability of system expertise none some some much
Degree of integration high high medium low
Condition/state of equipment good good fair poor
Age of system new medium medium old
Current level of reliability good good fair poor
System efficiency good good medium poor
Efficiency improvement
potential
good good medium poor
Recommended action: Repair and refill Drop-in Retrofit New system
8

Introduction
Characteristics of Selected Types of Equipment
Different types of equipment have certain characteristics associated with them, that
may affect some aspects of the decision-making and some of these are listed in the
Characteristics of Selected Types of Equipment sheet
Application example System Type Relative Charge
Integrated into
Application
Domestic refrigeration integral small low
Stand alone retail food display and
vending
integral small low
Condensing unit refrigeration remote medium medium
Large supermarket systems distributed large medium
Cold storage remote large medium
Industrial process refrigeration all medium, large high
Refrigerated transport remote medium high
Split and ducted air conditioners remote medium medium
Portable & window air conditioner units integral small low
Heat pumps all medium, large medium
Chillers integral medium, large medium
Mobile air conditioning (MAC) Integral small high
9

Introduction
Further information
The information within this manual was drawn from a variety
of different sources. However, rather than providing a detailed
reference list, each chapter is accompanied by a short list of
publications for further reading. These publications cover a large
amount of information on the topics addressed within this manual.
There are also a large number of textbooks on the subject of
refrigeration engineering, and a selection of those is listed below.
Amongst these, are addressed many of the topics covered within
this manual, particularly related to servicing and maintenance
practices:
Air Conditioning and Refrigeration, by R Miller and M R Miller, 2006
Modern Refrigeration and Air Conditioning, by A D Althouse, C H Turnquist,
and A F Bracciano, 2004
Principles of Refrigeration, by R J Dossat and T J Horan, 2001
Refrigeration and Air Conditioning Technology, by B Whitman, B Johnson, J
Tomczyk, E Silberstein, 2008
Refrigeration Equipment: A Servicing and Installation Handbook, by A C
Bryant, 1997
More generally, there exist a large number of organizations who
have Internet sites from where extensive information can be found
related to the subjects of refrigeration and refrigerants.
A selection are:
4 www.ammonia21.com - related to the ammonia refrigeration industry
4 www.ashrae.org
American Society of Heating, Air-conditioning and Refrigeration Engineers
4 www.eurammon.com
Eurammon - the European trade association for the use of natural
refrigerants
4 www.hydrocarbons21.com
Hydrocarbons21 - related to the hydrocarbon refrigeration industry
4 www.iiar.org - International Institute of Ammonia Refrigeration
4 www.iifiir.org - International Institute of Refrigeration
4 www.r744.com
Everything R744 - related to the carbon dioxide refrigeration industry
4 www.refrigerantsnaturally.com
Refrigerants, Naturally! - an organization of end-users involved in the
adoption of natural refrigerants
4 www.unep.org/ozone/
UNEP Ozone Secretariat – website of the Secretariat of the Vienna
Convention and the Montreal Protocol: Ozone Secretariat
4 www.uneptie.org/ozonaction
UNEP DTIE OzonAction – website of the OzonActon Branch as an
implementing agency and clearinghouse function
10

Introduction
Another form of reference information pertinent to the application of
refrigeration systems and refrigerants is standards, which are usually
a description of procedures or technical requirements that should
enable individuals or companies to achieve equivalence in the
activity under consideration.
For example, following refrigeration safety standards should ensure
that two separate refrigerating systems achieve an equivalent
level of safety, and following performance standards should
ensure that two separate organizations would measure the same
performance of the same system. Furthermore, they are intended
to help practitioners avoid problems, errors and pitfalls that they
may otherwise encounter if they did not follow the guidance of the
standards.
Standards are published by a variety of different organizations.
At a country level, national standardization bodies publish
national standards (although in many cases these may be
based on other countries’ standards or international standards).
European standardization bodies publish a European standard,
which are typically adopted by national standardization bodies
within European countries. Internationally, there are two main
organizations which publish international standards.
The numbers of national, European and International standards that
apply to the RAC sector are vast, and the reader should seek out
the most relevant ones when and where necessary.
Here, a small selection of such standards is listed to provide an indication of
what may be relevant to this subject area:
EN 378: 2008 – Refrigeration systems and heat pumps, safety and
environmental requirements;
This is comprised of four parts
• Part 1: basic requirements, classification and selection criteria
• Part 2: design, construction, testing, marking and documentation
• Part 3: Installation site and personal protection
• Part 4: Operation, maintenance, repair and recovery
EN 13313: 2008 – Refrigeration systems and heat pumps, Competence of
personnel; this addresses the level of competence that is necessary
for engineers and technicians to carry out different activities
ISO 817: 2005 – Refrigerants – designation and system classification; this
covers the R-numbering system for refrigerants and the means for
their safety classification
ISO 5149: 1993 – Mechanical refrigerating systems used for cooling and
heating – Safety requirements; this current version is rather dates, but
it is currently under revision and is similar to EN 378
ISO 916: 1968 – Testing of refrigerating systems; this covers the
determination of the technical performance of a refrigerating
system (but not the functional duty of a complete installation or the
performance of its individual components)
11

Introduction
Other International and European standards, as well as various national
standards also address the following subject matter:
Properties of refrigerant and lubricants
Performance testing of systems including energy consumption
(refrigeration, air conditioners, heat pumps, etc) and components
Performance of refrigeration-related equipment (such as recovery,
recycling, vacuum equipment)
Performance testing of refrigerated display equipment, and refrigerated
storage equipment
Design, construction and selection of system safety devices (such as
pressure relief and pressure limiting devices)
Safety design, construction and selection of system components (such as
vessels and pipes)
Safety of appliances (such as domestic refrigerators and freezers,
commercial refrigerating equipment, air conditioners, dehumidifiers and
heat pumps)
Testing of airborne noise levels of refrigeration, air conditioners, heat pump
equipment
Electrical safety of refrigeration, air conditioners, heat pump equipment
Such standards can be obtained from the relevant standardization
organizations:
4 www.iso.org - International Standardisation Organisation
4 www.cen.eu - Comité Européen de Normalisation
4 www.iec.ch - International Electro-technical Commission
4 www.cenelec.eu - Comité Européen de Normalisation Electrotechnique
12

Introduction
Choose your chapter
Throughout the lifetime of the equipment, a variety of activities
are carried out by different personnel and accordingly, a range
of knowledge is needed. The content of this manual is intended
to provide a large portion of that, particularly for those who are
involved in refrigerant handling. We have summarised the major
activities involved during the start-of-life, operation and end-oflife
stages of RAC equipment. For each of these activities, the
most important chapters of this manual have been identified.
Thus, any training course or technical guidance specifically for any
one of these activities can be focused on the material within the
corresponding chapters.
The primary objective of this
manual is to provide the reader
with the appropriate background
information to enable him/her to gain
an adequate level of understanding
related to the key topics addressed.
The diagram on the next page
summarizes the contents of this
manual.
13

Introduction
END OF LIFE OPERATION
START OF LIFE
Click on any
of the chapter
bars to visit
that section
DESIGN
ASSEMBLY
INSTALLATION
COMMISSIONING
MAINTE
-NANCE
SERVICE
DECOMMISSIONING
DISPOSAL
CHAPTER 1
ENVIRONMENTAL
IMPACT
sets the overall
context for the
manual, being
the environmental
impact of refrigerants
and thus
the introduction
of alternative
refrigerants
CHAPTER 2
REFRIGERANTS
provides a broad
overview of most
of the issues
associated with
refrigerants.
CHAPTER 3
REFRIGERANTS
MANAGEMENT
covers a variety of
important aspects
related to the
handling and
management of
refrigerants, with
the primary focus
on maintaining good
quality refrigerant
and avoiding
emissions and
wastage.
CHAPTER 4
SERVICING
PRACTICES
covers methods
and techniques
that are used when
working on
systems, primarily
during servicing
exercises.
CHAPTER 5
RETROFITTING
addresses the
approach and
working procedures
for changing
refrigerants within
an existing system.
14
CHAPTER 6
SAFE REFRIGERANT
HANDLING
covers the relevant
safety with refrigerants.
There is a general
description of the
safety implications
of refrigerants,
including toxicity,
oxygen displacement,
flammability, degradation
products, and high
pressure to highlight
the major hazards.

1
Environmental
impact of
refrigeration and
air conditioning
(rac) systems
Content
The ozone layer 4
The ozone layer and the Montreal Protocol 4
Effects of ozone layer depletion on the environment 4
Alternative refrigerants and regulations 4
The way forward 4
Further reading 4

1
Summary 1.1. Introduction
Initially the ozone layer is described and the impact
that certain refrigerants have on it. The concept of
global warming is also described and the impact of
some refrigerants, and the energy-related impact
associated with the operation of refrigeration
systems are discussed. The primary motivation for
the introduction of alternative refrigerants, namely the
Montreal Protocol and latterly the Kyoto Protocol are
emphasized.
The reader should be able to:
• Identify the main environmental problems related
to RAC installations
• Identify the role of chlorofluorocarbon (CFC) and
hydrochlorofluorocarbon (HCFC) refrigerants in
ozone layer depletion
• Identify how RAC contributes to global warming
• Identify the measures of the Montreal Protocol
and the schedule for refrigerants phase-out.
Environmental Impact
Refrigeration, air conditioning and heat pump applications represent
the major consumer of halogenated chemical substances used as
refrigerants; it is also one of the most important energy sector users
in our society today. It is estimated that, on average, for developed
countries, the RAC sectors are responsible for 10-20% of electricity
consumption.
The economic impact of refrigeration applications is significant;
estimates indicate 300 million tonnes of continually refrigerating
goods, with huge annual electricity consumption, and about US$
100 billion in equipment investments, where the estimated value of
the products treated by refrigeration are about four times this sum.
This is one of the reasons why economic impacts of the elimination
of refrigerant chemical substances such as CFCs and in the near
future HCFCs have been hard to calculate.
Although HCFCs had been used since the 1930s, because of
their relatively low ozone depleting potential (ODP), they were not
at first included in the controls for ODS. As such, they were used
within mixture of other chemical compounds to enable the easy
replacement of CFCs. It was, however, acknowledged at the time
that these chemicals were transitional since their production and
consumption was also to be phased out under the Montreal Protocol.
About The Ozone Layer 4
About the Montreal Protocol 4

1
Environmental Impact
The ozone layer
As the sun’s radiation approaches the planet’s surface it can be
scattered, reflected, or absorbed, intercepted and re-emitted. This
is where the ozone layer comes into its own by scattering and
reflecting harmful high energy ultraviolet radiation. Variations in
temperature and pressure divide the Earth’s atmosphere into layers
and the mixing of gases between the layers happens very slowly.
That is why this 90% of the ozone stays in the upper atmosphere.
This stratospheric ozone contains 90% of all ozone gas on the
Earth but it is spread thinly and unevenly.
Life on earth has been safeguarded because of a protective layer
in the atmosphere. This layer, composed of ozone, acts as a shield
to protect the earth against the harmful ultraviolet radiation from
the sun. Ozone is a form of oxygen with three atoms (O3) instead of
two (O2). Through natural atmospheric processes, ozone molecules
are created and destroyed continuously. Ultraviolet radiation
from the sun breaks up oxygen molecules into atoms which then
combine with other oxygen molecules to form ozone. Ozone is not
a stable gas and is particularly vulnerable to destruction by natural
compounds containing hydrogen, nitrogen and chlorine.
Near the earth’s surface (the troposphere) ozone is an increasingly
troublesome pollutant, a constituent of photochemical smog and
acid rain. But safely up in the stratosphere, 11 to 48 km above the
earth’s surface, the blue, pungent-smelling gas is as important
to life as oxygen itself. Ozone forms a fragile shield, curiously
insubstantial but remarkably effective.
The distribution of ozone in the atmosphere is illustrated in Figure 1.1.
ALTITUDE (KILOMETERS)
35
30
25
20
15
10
5
0
OZONE LAYER
OZONE
INCREASES
FROM POLLUTION
OZONE CONCENTRATION
Distribution of ozone in atmosphere.
STRATOSPHERIC
OZONE
TROPOSPHERIC
OZONE
17
20
15
10
05
ALTITUDE (MILES)

1
Environmental Impact
1. The exosphere
(2400km))
The sunlight still contains very high-energy photons, which can heat gas
particles in the exosphere up to 2,500 degrees C during the day.
2. The ionosphere Most high energy photons are absorbed here leading to a few air
molecules becoming electrically charged.
3. The ozone layer This thin layer at the top of the stratosphere absorbs most of the ultraviolet
(UV) light. Too much UV light can cause damage to living things
so the ozone layer is very important in protecting life on Earth.
4.The stratosphere
(50km)
5. The troposphere (8-15
km).
6. Absorption of
radiation emitted by the
Earth
Ozone depletion relies on the clouds in the stratosphere: Polar
stratospheric clouds (PSCs), also known as nacreous clouds, are
CLOUDS in the winter polar STRATOSPHERE at altitudes of 15,000–25,000
metres (50,000–80,000 ft). They are implicated in the formation of OZONE
HOLES; [1] their effects on ozone depletion arise because they support
chemical reactions.
The troposphere contains most of the air molecules, nearly all the water
vapour so all of the clouds are in this layer. All these particles mean that
a lot of sunlight is scattered. Shorter wavelengths (violet and blue) are
scattered more than longer wavelengths, making the sky appear blue.
The Earth emits a lot of long wavelength radiation from its surface and
much of this is absorbed and scattered in the troposphere. Greenhouse
gases such as carbon dioxide and water vapour are responsible for
most of this absorption, making the temperature around the Earth
higher.
This ozone filter efficiently screens out almost
all the harmful ultraviolet rays of the sun; the
ozone layer absorbs most of the dangerous
UV-B radiation (radiation between UV-A which
is allowed through and UV-C which is mainly
captured by oxygen, as indicated in Figure
1.2). Any damage that is done to the ozone
layer will lead to increased UV-B radiation.
Increases of UV-B radiation have been clearly
observed in areas experiencing periods of
intense ozone depletion.
Any increased UV-B that reaches the earth’s
surface has a potential to cause considerable
harm to the environment and to life on earth.
A small decrease in the ozone layer could
significantly increase the incidence of skin
cancer, and could lead to an acceleration
of the rarer but more virulent form of
cancer known as coetaneous malignant
melanoma. Increased UV-B could lead to
increased incidents of eye damage, including
cataracts, deformation of the eye lenses, and
presbyopia. Eye cataracts, the leading cause
of blindness in the world, are expected to
increase considerably.
18

1
Environmental Impact
RADIATION FROM THE SUN
UV-B
Figure 1.2. Radiation from the sun
DONE
UV-A
OZONE LAYER
EARTH
UV rays are dangerous to human beings,
animals and plants because they burn. They
can penetrate our skin and eyes and weaken
our bodies’ immune system. That is why we
should avoid long periods in the sun. To get
the minimum daily dose of vitamin D only 15
minutes in the sun per day is enough. If we
stay more than that, we might get sunburnt if
no protection is used. Repeated sunburns and
frequent tanning can cause premature ageing
of the skin and, at worst, skin cancer such as
melanoma (because of UV-A and UV-B). For
the eyes the UV-B rays can cause a cataract
(clouding of the eye lens). Most of the serious
health problems appear only many years later.
CATEGORY WAVELENGTHS
(nanometres)
REACTIONS IN &
WITH
STRATOSPHERE
UV-A: 315/320 - 400 nm Not significantly
absorbed by the
stratospheric ozone
layer.
UV-B: 280 – 315/320 nm Absorbed by ozone
in the stratosphere.
Ozone absorbs UV
radiation without
being reduced; the
overall result being
to convert UV
radiation to heat.
UV-C: 200 - 280 nm Highly absorbed by
oxygen molecules:
involved with
formation of ozone.
EFFECT UPON
HUMANS, PLANTS ETC.
10-15% of ‘burning’:
possible connection with
the formation of skin
cancers. Responsible for
'tanning' & skin ageing.
85 – 90 % ‘burning’;
involved with both
malignant & benign
cancerous growths. Also
linked to eye cataracts.
Effects on growth of plants
and marine life. Strong
radiation kills also plankton
in the water which is the
main food supply for
fishes.
Not thought to be
significant, mainly because
of its efficient absorption
at high-altitudes.
19

1
Environmental Impact
Exposure to increased UV-B radiation could also suppress the body’s
immune system.
Immunosuppression by UV-B occurs irrespective of human skin
pigmentation. Such effects could exacerbate the poor health
situations of many developing countries.
Increased UV-B radiation could also cause decreased crop yields
and damage to forests. It could affect ocean life causing damage to
aquatic organisms, parts of the marine food web, which may lead
to a decrease in fish higher up the food chain. Materials used in
buildings, paints, packaging and countless other substances could
be rapidly degraded by increased UV-B.
Depletion of stratospheric ozone could aggravate the
photochemical pollution in the troposphere resulting in an increase
of ozone at the surface of the earth where it is not wanted. Earth
and inhabitants, therefore, have an enormous stake in preserving
the fragile ozone layer shield.
Global consensus supports the theory that chlorine and bromine
containing man-made chemicals emitted into the atmosphere are
responsible for the depletion of ozone in the stratosphere. The
larger part of these compounds, called ODS, consists of CFCs,
HCFCs and halons (used as fire extinguishing agents), which are
most effective in ozone depletion. CFCs have been used for years
as refrigerants, solvents or blowing agents. ODS are classified
considering how harmful they are for the ozone layer using a
parameter called ozone depleting potential (ODP).
ODP is a relative index indicating the extent to which a chemical
product may cause ozone depletion. The reference level of 1 is the
potential of R11 and R12 to cause ozone depletion. If a product
has an ODP of 0.5, a given weight of the product in the atmosphere
would, in time, destroy half the amount of ozone that the same
weight of R11 would destroy. ODP is calculated from mathematical
models which take into account factors such as the stability of the
product, the rate of diffusion, the quantity of depleting atoms per
molecule and the effect of ultraviolet light and other radiation on the
molecules.
20

1
Environmental Impact
The ozone layer and the Montreal Protocol
CFCs (ANNEX A/I) PRODUCTION/CONSUMPTION REDUCTION SCHEDULE
UNEP has been concerned about the protection of the
ozone layer since its inception in 1972. In March 1985,
the Convention for the Protection of the Ozone Layer
120 %
NON - A5
ARTICLE 5
CFC-NON-A5
was signed in Vienna. The Convention provided for future
protocols and specified procedures for amendment
and dispute settlement. In September 1987, agreement
100 %
BASELINE
1989
BASELINE
95-97
CFC-A5
was reached on specific measures to be taken and the
Montreal Protocol on Substances that Deplete the Ozone
80 %
Layer was signed. Under the Protocol, the first concrete
step to protect the ozone layer was taken, a 50%
60 %
reduction in the production and consumption of specified
CFCs by the year 1999.
Even as the nations adopted the Protocol in 1987, new
40 %
20 %
scientific findings indicated that the Protocol’s control
0 %
measures were inadequate to restore the ozone layer. In
JAN- JAN- JAN- JAN- JAN- JAN- JAN- JAN- JAN- JAN- JAN- JAN- JAN- JAN- JANaddition,
developing countries expressed concern over
the vague language both regarding technology transfer to
1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014
developing countries and regarding financial assistance.
MONTH/YEAR
As a result of the Second Meeting of the Parties in
London (1990), the Montreal schedules were adjusted so that the
five CFCs (R11, R12, R113, R114 and R115) and the three halons
Figure 1.3 Article 5 and Non-Article 5 countries phase-out schedules of
Annex A Group I CFCs
would be phased out by the year 2000. Methyl chloroform was to The UNEP Assessment Panels did a substantial amount of work in 1991. These
be controlled and to be phased out in 2005. Figure 1.3 shows the Panels consider the science, the effects and the technology that is in place to
CFC phase-out schedules for Article 5 and Non-Article 5 countries. replace and phase out the controlled chemicals.
21

1
Environmental Impact
On the basis of these reports the parties to the Montreal Protocol
discussed again a tightening of the control schedules.
Achieving the goals of the Montreal Protocol depends on
widespread cooperation among all the nations of the world. It is not
enough that the developed nations, which accounted in 1986 for
85% of the consumption of ODS, participate in the Protocol. The
participation of developing countries, which consumed only 15%
in 1986, is also vitally important. HCFC consumption in developing
countries has been growing at a much higher rate than in the
developed world.
As long ago as 1987, developing countries were given incentives
to conform with the Protocol in the form of a grace period of 10
years for implementation and technical assistance (Articles 5 and
10 in the Protocol). However, by 1989 many of the larger developing
nations indicated that the provisions were inadequate. They argued
that it was not they that were responsible for depleting the ozone
layer. And as they are just beginning to develop economically and
to use the low cost CFC technology acquired from the developed
countries, they require help with the costs. If they are to bind
themselves to strict schedules for adopting new technologies, they
need to be given the new technologies and the finance necessary to
adopt them. Negotiations on this issue resulted in the establishment
of a new financial mechanism in London, 1990, through a new
Article 10 in the Montreal Protocol.
The mechanism includes a Multilateral Fund and other multilateral,
regional and bilateral co-operation. The Fund has now operated
since 1991; under the Fund, UNEP OzonAction is responsible for
information dissemination, training and networking. This manual
is part of UNEP’s work programme related to training on good
practices in refrigeration in developing countries.
What is your countries protocol status from
4 http://ozone.unep.org/Ratification_status/list_of_article_5_parties.
shtml
Contact your National Ozone Units/Officers available on
4 http://www.uneptie.org/ozonaction/information/contacts.htm
to find out actions being taken by your government.
Although having considerably lower ODP than CFCs, many HCFCs
have high global warming potentials (GWP), of over 2000 times that
of carbon dioxide (CO2).
The reasons for the phasing out
For the impacts on climate change
and global warming
Effects of Ozone Depletion 4
Global Warming 4
Key dates in refrigeration development, a summary of what is happening
and deadlines before different refrigerants become illegal to use.
Timeline Activity 4
22

1
Environmental Impact
Effects of ozone layer depletion on the
environment
With the loss of the shield from ultraviolet radiation, serious damage can
result on all living organisms. The severity of the situation is augmented
by the fact that each one percent depletion of ozone results in up to two
percent increased exposure to ultraviolet radiation.
Plant and marine life could be adversely affected by increased
exposure to ultraviolet radiation caused by depletion of the ozone
layer. The sensitive ecosystem of the oceans may be adversely
affected. The phytoplankton and larvae of many species that live
from the surface of the ocean down to several metres below the
surface could well be sensitive to increased exposure to ultraviolet
radiation. Increased exposure results in reduced productivity, which
means less plant life and fewer fish harvested from the seas.
The Global Solar UV Index, developed by the World Health
Organization in collaboration with UNEP and the World
Meteorological Organisation, is a tool to describe the level of UV
radiation at the Earth’s surface. It uses a range of values from zero
upwards, taking into account all the factors to indicate the potential
for adverse health effects due to UV radiation. The higher the value,
the greater the amount of dangerous UV rays.
UV factors High UV radiation
Time of the day Between 10 am to 4 pm
Time of the year Summer or hot season
Location Especially close to the equator and poles
Elevation Altitude above sea level
Reflection Sand, snow, water and ice
Weather No dark clouds in front of the sun
Activity
Fortunately there are many easy ways to protect ourselves from these
dangerous rays. Use that information to write out a four point action plan.
• During the hot season avoid the sun between 10 am and 4 pm
when the UV Index is the highest.
• Search for a shade when you’re outside. Under a tree there might
be up to 60% less radiation than in a sunny place.
• Cover your skin and eyes. Wear long sleeves, trousers, a hat or
something to cover your head and sunglasses to protect your eyes.
• Use sunscreen. If you want to go swimming, avoid the midday
hours and use sunscreen for the whole body as the water
reflects the rays efficiently and increases the radiation. Also
while wearing a long-sleeved shirt use some sunscreen on your
hands or other parts that are not covered. Sunscreen should
also be used often; if you put it once and stay in the sun for
hours that is not enough to well protect your skin. Also every
time you go swimming you should add sunscreen afterwards.
23

1
Environmental Impact
Global warming
The earth’s temperature is maintained by a balance between
heating from solar radiation flowing in from the sun, and cooling
from infrared radiation emitted by the earth’s warm surface and
atmosphere escaping back to into space. The sun is the earth’s only
external source of heat. When solar radiation, in the form of visible
light, reaches the earth, some is absorbed by the atmosphere and
reflected from clouds and land (especially from deserts and snow).
CHAPITRE 1
The remainder is absorbed PAGE 24 by the surface which is heated and in
THE CONCEPT OF GLOBAL WARMING
turn warms the atmosphere. The warm surface and atmosphere
of the earth emit invisible infrared radiation. While the atmosphere
is relatively transparent to solar radiation, infrared radiation is
absorbed in the atmosphere by many less abundant gases. Though
present in small amounts, these trace gases act like a blanket,
preventing much of the infrared radiation from escaping directly
to space. By slowing
SUN
the release of cooling
SUN’S RADIATION
radiation, these gases
warm the earth’s surface.
This process is illustrated
here:
GREENHOUSE GASES
EARTH
TROPOSPHER
INFRARED RADIATION BEING TRAPPED
The concept of global warming
In a greenhouse, glass allows sunlight in but prevents some infrared
radiation from escaping. The gases in the earth’s atmosphere
which exert a similar effect are called “greenhouse gases” (GHGs).
Of the man-made greenhouse gases, the most important are
carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and the
halocarbons (CFCs, HCFCs and HFCs).
Different gases absorb and trap varying amounts of infrared
radiation. They also persist in the atmosphere for differing time
periods and influence atmospheric chemistry (especially ozone) in
different ways. For example, a molecule of R12 has about the same
effect on radiation as 16,000 CO2 molecules. A molecule of methane
has approximately 21 times the effect of CO2; but its lifetime is far
shorter. The GWP is an index which compares the warming effect
over time of different gases relative to equal emissions of CO2
(by weight). A table of the ODP and GWP of various refrigerants
is included in Chapter 2. HFCs do not have chlorine, and in this
way, don’t destroy the ozone layer, but they do contribute to global
warming. For this reason, they are in the group of gases controlled
by Kyoto Protocol. These gases are: CO2, CH4, N2O, HFCs,
perfluorocarbons (PFCs) and sulphur hexafluoride (SF6).
Scientific measurements have shown that in the last century, the
Earth’s average near-surface atmospheric temperature rose 0.6 ± 0.2
°C, mostly attributable to human activities increasing the concentration
of CO2 and other greenhouse gases in the atmosphere. Moreover, a
global temperatures increase by between 1.4 and 5.8 °C between 1990
and 2100 has been predicted by the models and disseminated by the
Intergovernmental Panel on Climate Change (IPCC).
24

1
Environmental Impact
The greenhouse warming effect causes an increase in global
temperatures and consequently potentially catastrophic effects,
such as rising sea level, changes in the amount and pattern of
precipitation, increasing the frequency and intensity of extreme
weather events, higher or lower agricultural yields, glacier retreat,
and so on. These are the reasons why the international community
has decided to control the emissions of GHGs through the Kyoto
Protocol signed in 1997 and entered into force in 2005.
Direct global warming of refrigerants
The halocarbons, and among them the main refrigerants, absorb
the infrared radiation in a spectral range where energy is not
removed by CO2 or water vapour, thus causing a warming of the
atmosphere. In fact these halocarbons are strong GHGs since their
molecules can be thousands of times more efficient at absorbing
infrared radiation than a molecule of CO2. CFCs and HCFCs have
also a significant indirect cooling effect, since they contribute to
the depletion of stratospheric ozone that is a strong UV radiation
absorber, but this effect is less certain and should vanish with
the reduction of the ozone hole. The direct warming potential of a
molecule is proportional to its radiative effect and increases with
its atmospheric lifetime. The direct global warming effect of a given
mass of substance is the product of the GWP and the amount of
the emissions: this explains why CO2 has a much greater overall
contribution to global warming than halocarbons, since the total
mass of CO2 emitted around the world is considerably more
massive than the mass of emitted halocarbons.
Direct emissions of GHGs may occur during the manufacture of the
GHG, during their use in products and processes and at the end of
their life. Thus, the evaluation of their emissions over all their life,
cycle is necessary. It is noteworthy that at present a large amount of
halogenated refrigerants is in banks (i.e. CFC, HCFC and HFC that
have already been manufactured but have not yet been released into
the atmosphere such as contained in existing equipment, products
and stockpiles, etc.) It is estimated that in 2002, the total amount
of refrigerants (CFC and HFC) banked in domestic refrigeration,
i.e. the sum of refrigerant charge contained in all refrigerators in
operation or wasted, amounted to 160,000 tonnes. Despite the fall
in the production of CFCs, the existing bank of CFCs, as refrigerant
in all RAC applications and including the amount contained in
foams, is over 1.1 million tonnes and is therefore a significant
source of potential emissions. Banks of HCFCs and HFCs are
being established as use increases. The management of CFC and
HCFC banks is not controlled by the Montreal Protocol or taken
into account under the United Nations Framework Convention on
Climate Change (UNFCCC). The emission of these banks could give
a significant contribution to global warming in the future.
Energy-related contribution to global warming
When considering the global warming impact of RAC equipment,
one should address both the “direct” emissions, and the energyrelated
emissions. When these two contributions are added
together, it provides and overall appreciation of the greenhouse gas
impact of the equipment as a whole. The direct emissions are those
of the refrigerant itself, for example, when the refrigerant leaks out,
or when it is released during servicing or disposal.
The energy-related contribution is represented by the emissions
of GHGs (mainly CO2) that arise from the production of electricity
from, for example, fossil fuels. Over the entire life cycle of the RAC
equipment, considerable amounts of electricity will be consumed,
and in many countries, this is mainly generated through the burning
of high-carbon content fuels, such as coal, oil and gas. In certain
25

1
Environmental Impact
countries which rely heavily on hydro-electricity or other renewable
energy resources (such as solar, wind, geothermal, and biomass),
or nuclear power, there are minimal emissions of CO2 per kWh
of electricity consumed. In countries that use carbon-intensive
electricity production, emissions can be around 1 kg of CO2 per
kWh. In these countries, the energy used is often the dominant
contribution to equipments’ GHG emissions. Therefore, it is
important to also improve and maintain the efficiency of RAC
equipment over its entire lifetime.
Certain concepts are often used to evaluate the overall lifetime GHG
impact of RAC systems. These include a variety of names: Total
Equivalent Warming Impact (TEWI), Life Cycle Climate Performance
(LCCP), and Life Cycle Warming Impact (LCWI), amongst others.
Essentially, all these concepts are the same: they add the total
equivalent GHG emissions from different sources together, over the
lifetime of the equipment. The purpose of doing this is often used to
compare different technologies, and more constructively, to identify
which aspects of the equipment could be most effectively optimised
to help reduce its global warming impact. Lastly, it is of utmost
importance to carry out such evaluations with attention to detail,
since there are myriad assumptions involved, and as such it is easy
to draw erroneous conclusions.
The Earth has a natural temperature control system. Certain
atmospheric gases are vital in this system and are known as
greenhouse gases. The Earth’s surface becomes warm and as a
result of incoming solar radiation and then emits infrared radiation.
The greenhouse gases trap some of the infrared radiation thus
warming the atmosphere. Naturally occurring greenhouse gases
include water vapour, carbon dioxide, ozone, methane and nitrous
oxide: together they create a natural greenhouse effect. Without this
phenomenon the Earth’s average temperature would be more than
30°C (60 °F) lower throughout the year.
Global warming might also slow down the ozone layer’s recovery;
despite the temperature rise in the troposphere, the air might even
cool down in the stratosphere, which is favourable to the depletion
of the ozone layer. The heat budget is dynamic – it is changing.
For example: at the time of the dinosaurs there was more carbon
dioxide in the atmosphere, trapping more heat, creating a higher
planetary temperature. This is an example of a feedback system.
Activity
Affect Increase Earth’s
Temperature
Cutting down forests will: √
26
Decrease Earth’s
Temperature
A major volcanic eruption will: √ √
Burning fossil fuels leading to increased
carbon dioxide in the atmosphere will:
The addition of CFCs will: √
The addition of HCFCs will: √
The addition of HFCs will: √
√
(May also offer
some cooling as
particles in the
atmosphere
reflect the sun’s
rays)

1
Environmental Impact
Timeline activity
An overview of refrigerant development, phase out CFC and Phase out HCFC
are given here:
19th Century
Refrigeration technology using the thermodynamic vapour
compression cycle technology was first developed in the middle
of the 19th Century. The technology used four basic components
(compressor, condenser, evaporator and device expansion) and a
working fluid, called a refrigerant. Since then, the RAC industry has
evolved significantly, and has been present in many social sectors.
1930s
CFC and HCFC refrigerants were developed and have been used in
the 1930s and 1940s.
1970s
During the 1970s CFC and HCFC refrigerants were found to be
directly connected to a global environmental problem: the depletion
of the ozone layer.
1987
CFC and HCFC are scheduled to be eliminated by the Montreal
Protocol, an international agreement established in 1987. As well
as contributing to the depletion of the ozone layer, CFCs and
HCFCs are strong greenhouse gases, thus contributing to the
global warming process. Since the establishment of Montreal
Protocol, the refrigeration industry has been searching substitutes
to CFCs and HCFCs refrigerants. At the same time, the industry
has been developing ways to conserve these refrigerants, making
the installations more leak-tight, adopting procedures for recovery
and treatment of refrigerants for re-use, and converting installations
to use zero ozone depleting substances (ODS) and low-global
warming refrigerants. These procedures are now part of the socalled
good practices of RAC servicing, and this manual has the
objective of summarise them, helping technicians to deal with the
upcoming challenges within the field of RAC.
2006
Global HCFC production was 34,400 ODP tonnes and approximately
75% of global HCFC use was in air-conditioning and refrigeration
sectors. The main HCFC used is R22 or chlorodifluoromethane.
2007
At the 20th anniversary meeting of the Montreal Protocol on
Substances that Deplete the Ozone Layer, in Montreal, agreement
was reached to adjust the Montreal Protocol’s schedule to
accelerate the phase-out of production and consumption of
HCFCs. This decision will result in a significant reduction in ozone
depletion, with the intention of simultaneously reducing the global
warming impact. In addition to the HCFC accelerated phaseout
schedules, the 2007 Meeting of the Parties of the Montreal
Protocol approved a decision to encourage Parties to promote the
selection of alternatives to HCFCs that minimise environmental
impacts, in particular impacts on climate, as well as meeting
other health, safety and economic considerations (Decision XIX/6:
Adjustments to the Montreal Protocol with regard to Annex C,
Group I, substances or so-called HCFCs).
27

1
Environmental Impact
Here are the schedules for HCFC phase-out schedules for Article 5
(developing) countries and Non-Article 5 countries:
Article 5 countries HCFC phase-out schedules
(production and consumption)
Level Year
Baseline Average of 2009 and 2010
Freeze 2013
10% reduction (90% of baseline) 2015
35% reduction (65% of baseline) 2020
67.5% reduction (32.5% of baseline) 2025
Total phase-out
2.5 % of baseline averaged over ten years
(2030-2040) allowed, if necessary, for
2030
servicing of refrigeration and air-conditioning
equipment until 2040
2030-2040
Non-Article 5 countries HCFC phase-out schedules
(production and consumption)
Level Year
Baseline
1989 HCFC consumption + 2.8%
of 1989 consumption
Freeze 1996
35% reduction (65% of baseline) 2004
75% reduction (25% of baseline) 2010
90% reduction (10% of baseline) 2015
Total phase-out
0.5 % of baseline restricted to servicing of
2020
refrigeration and air-conditioning equipment
until 2030
2020-2030
28

1
Environmental Impact
Alternative refrigerants and regulations
Hydrofluorocarbon (HFC) refrigerants were developed in the 1980s
and 1990s as alternative refrigerants to CFCs and HCFCs. HFCs
do not contain chlorine, and therefore do not destroy the ozone
layer. They do, however, contribute to global warming; HFCs are
greenhouse gases and as such they are in the group of gases
included within the Kyoto Protocol. Several regions and countries in
the world are adopting regulations to contain, prevent and thereby
reduce emissions of the fluorinated greenhouse gases covered by
the Kyoto Protocol.
Examples of regulation:
European 4
USA 4
29

1
Environmental Impact
European
One example is regulation (EC) no 842/2006 of the European
Parliament. It applies to several HFC compounds, among them the
R134a, and R404A.
According to this Regulation, for stationary refrigeration, air conditioning
and heat pump units over 3 kg charge (6 kg if hermetic), operators must:
• Prevent leakage, and repair any leaks as soon as possible
• Arrange proper refrigerant recovery by certified personnel during
servicing and disposal
• Carry out regular leak checks (e.g. at least once every three
months for applications with 300 kg or more of fluorinated
gases) by certified competent staff
• Maintain records of refrigerants and of servicing
• Provide labelling of equipment containing fluorinated gases
• Prohibit of placing on the market certain equipment containing
fluorinated gases such as non-refillable containers.
For non-stationary equipment (e.g., mobile units on trucks) and any
other products containing fluorinated gases, operators must ensure
that appropriately qualified personnel are used to recover gases, as
long as this is feasible and not excessively expensive.
Other European measures regarding the use of HFCs are covered by
the Directive 2006/40/EC, relating to emissions from air-conditioning
systems in motor vehicles, which bans fluorinated gases with a GWP
higher than 150 (such as R134a) as of 2011 for new models of cars.
USA
Another case of regulations concerning the use of HFC compounds
are the measures adopted by the California Air Resources Board
in 2007, to reduce the HFC emissions from mobile vehicle air
conditioning (MVAC) systems. These measures will control HFC
releases from MVAC servicing, requiring leak tightness test, repair
to smog check, enforce the federal regulations on banning HFC
release from MVAC servicing, dismantling, and require using low-
GWP refrigerants for new MVAC.
Mobile Vehicle Air Conditioning manufacturers are testing
alternative refrigerants to meet the long-term needs of automotive
manufacturers. Currently there are two alternatives under
consideration: R744 (carbon dioxide) and R1234yf (an unsaturated
HFC). Both have low GWP, are of lower toxicity, and whilst R744
is non-flammable, R1234yf has a lower flammability classification.
These new alternatives are still in the testing and development
phase, and it is not clear whether either one or both will be adopted
for MVAC systems.
With the continued environmental pressure on refrigerants,
technological innovations have helped in the consideration of
“natural refrigerants” (ammonia, hydrocarbons, carbon dioxide) as
a safe and economic options for RAC applications in many areas.
Because of smaller environmental impacts and for being more
appropriate in terms of sustainable technological development
perspective, refrigeration systems with natural refrigerants could
have an important role in the future as technical solution in many
applications.
30

1
Environmental Impact
The way forward
Changing refrigerant options and efficiency goals are likely to drive
further innovations in air conditioning and refrigeration equipment.
Technical options are being developed to lower refrigerant charges
in equipment, thereby decreasing refrigerant emissions, and
cooperating for the responsible use of all alternatives. Due to
technological development and adoption of sustainability policies,
it is predicted an increase of natural refrigerant applications. Use of
indirect systems (applying heat transfer fluids in secondary systems)
is growing since it helps also to reduce charge sizes, to enable
use of sealed systems, and to facilitate application of flammable
alternatives.
Contrary to non-Article 5 countries, the demand for service
refrigerants in most Article 5 countries will consist of CFCs and
HCFCs, a tendency driven by long equipment life and with the costs
of field conversion to alternative refrigerants, and the availability
of such alternatives. One of the main concerns will be maintaining
adequate supplies of HCFCs. Refrigerant conservation programmes
to be established for CFCs in Article 5 countries will mostly be
government sponsored and regulatory in nature. As in many non-
Article 5 countries, they may include restrictions on the sale, use,
and end-of-life disposal requirements that mandate recovery and
recycling of refrigerants. These programmes will be expanded in
countries without such requirements.
Further reading
UNEP DTIE OzonAction – Ozone Protection, Climate Change & Energy
Efficiency, Centro Studi Galileo / UNEP, 2007
4 www.unep.fr/ozonaction/information/mmcfiles/4824-eozoneclimenerg.pdf
Ozone Secretariat, Refrigeration – reports of the Air Conditioning and Heat
Pumps Technical Options Committee (RTOC)
4 www.ozone.unep.org/teap/Reports/RTOC/
UNEP DTIE OzonAction – Protecting the Ozone Layer, Volume 1,
Refrigerants, UNEP, 2001
4 www.unep.fr/ozonaction/information/mmcfiles/2333-e.pdf
International Panel on Climate Change - IPCC special report on
Safeguarding the Ozone Layer and the Global Climate System: Issues
related to Hydrofluorocarbons and perfluorocarbons, IPCC / TEAP, 2005
4 www1.ipcc.ch/ipccreports/sroc.htm
European Commission Environment - web section on fluorinated
greenhouse gases
4 http://ec.europa.eu/environment/climat/fluor/index_en.htm
31

2
Refrigerants Content
Selecting the refrigerant 4
Types of refrigerants 4
Refrigerant numbering 4
Refrigerant blends 4
Using Refrigerant Blends – issues and concepts 4
Lubricants 4
Refrigerants and applications 4
Further reading 4

2
Refrigerants
2.1. Section objectives
This chapter provides a broad overview of most of the issues
associated with refrigerants. This includes the criteria normally
applied to their selection (for example, thermodynamic
properties and safety characteristics), an overview of the
various types of refrigerants and how they are identified.
Particular attention is paid to the characteristics of refrigerant
blends. Although not normally considered to be a refrigerant,
the topic of refrigeration oils or lubricants is discussed since
it effectively becomes part of the working fluid during system
operation and thus requires special attention also.
The information provided here should help the reader
to be able to:
• Identify refrigerant characteristics
• Recognise the classification of refrigerants
• State the main refrigerant groups
• Identify the proper refrigerant for each refrigeration or
air-conditioning system
• State the main characteristics for the most commonlyused
refrigerant
• Identify the suitable lubricant for each refrigerant.

2
Refrigerants
Selecting the refrigerant
Originally when the modern refrigerating system concept was
developed in the middle of the 19th Century, a small number
of fluids were used as the working fluid, or “refrigerant”. These
included ammonia (NH3, R717), carbon dioxide (CO2, R744),
sulphur dioxide, methyl chloride and ethyl ether. However, because
of the combination of toxicity, flammability and pressure issues,
these refrigerants were largely replaced with to a “new” group of
fluorinated chemicals which exhibited little reactivity, low-toxicity
and no flammability. However, during the 1980s, it was found that
these chemicals contributed to the depletion of the ozone layer,
which lead to the development of the Montreal Protocol in 1987.
The Montreal Protocol requires the cessation of the consumption
and production of all chlorofluorocarbons (CFCs) and
hydrochlorofluorocarbons (HCFCs) and since its introduction, the
refrigeration and air conditioning (RAC) industry has been engaged
with the chemical community to establish substitutes for ozone
depleting refrigerants. Throughout this time a large number of
refrigerants have been introduced worldwide, of which some are
long term alternatives, and others are “transitional” substances.
With the increasing attention paid to the issue of global warming
and climate change, there is now a stronger push towards adopting
alternative refrigerants with low or no global warming potential
(GWP), as well as zero ozone depleting potential (ODP).
With the continued attention on replacement refrigerants, coupled
with the ever growing market for RAC, there are now several
hundred refrigerants that are currently commercially available. Such
a diversity of refrigerants and their variety of different characteristics
can create difficulties in handling and servicing practices for many
RAC technicians. This section aims to introduce an overview of
refrigerants and their characteristics, classifications, applications,
identification and lubricants.
There are usually two situations that necessitate refrigerant selection,
the first being for manufacture of systems, and the second being
equipment servicing. For manufacturing RAC equipment, the
refrigerant selection process is theoretically complex, involving the
CHAPITRE 2
consideration of huge number parameters.
PAGE 03
THERMODYNAMIC
AND TRANSPORT
PROPERTIES
CHEMICAL
PROPERTIES
AND STABILITY
SELECTION CRITERIA
ALTERNATIVES
COST
AND
AVAILABILITY
34
OPERATING
PRESSURES
SAFETY
CHARACTERISTICS

2
Refrigerants
Chemical properties and stability
The stability of a refrigerant is linked to the way it behaves in the
presence of other substances, particularly within the refrigerating
system. It is important that the refrigerant will not react with, or act
as a solvent with, any of the materials within the system. These
include metals used for pipes and other components, compressor
oils and associated additives, plastic motor materials, elastomers
in valves and fittings, and desiccants within filter dryers. This
should also be considered with respect to the small quantities of
contaminants such as moisture and air.
In general CFCs, HCFCs, hydrofluorocarbons (HFCs) and HCs
are compatible with most materials (since most components are
designed for these refrigerants). However, many components are
designed using proprietary mixtures and additives, so there is always
a possibility of incompatibility with certain materials if an unspecified
refrigerant is used. Carbon dioxide has some compatibility problems
with certain elastomers, which is why only dedicated components for
R744 should be used with this refrigerant.
Ammonia is not compatible with many materials, such as copper,
copper alloys and many electrical wiring insulation materials.
Therefore construction metals inside ammonia systems are normally
limited to carbon steel and stainless steel.
In all cases, component manufacturers should be consulted to check
that their materials are compatible with a non-standard refrigerant.
Operating pressures
It is important to consider the likely operating pressures in both the
suction and discharge sides of the system. Ideally, a refrigerant is
chosen that will have an evaporating pressure above atmospheric
pressure under normal operating conditions, so as to avoid air and
moisture being drawn into the system in the event of a leak. Thus, a
refrigerant should be chosen with a normal boiling point (NBP) that
is lower than the anticipated evaporating temperature. A selected
refrigerant should also have a condensing pressure that does not
exceed the pressure that the system components are designed for,
as this can have safety implications.
Thermodynamic and transport properties
The most important performance criteria for a refrigerating system
are cooling (or heating in the case of heat pumps) capacity and
efficiency, or coefficient of performance (COP). These performance
characteristics are influenced by a number of properties, including:
• saturation pressure-temperature characteristics
• critical temperature
• latent heat
• density
• viscosity
• thermal conductivity
• specific heat capacity
35

2
Refrigerants
It is important to consider the likely operating pressures in both the
suction and discharge sides of the system. Ideally, a refrigerant is
chosen that will have an evaporating pressure above atmospheric
pressure under normal operating conditions, so as to avoid air and
moisture being drawn into the system in the event of a leak. Thus, a
refrigerant should be chosen with a normal boiling point (NBP) that
is lower than the anticipated evaporating temperature. A selected
refrigerant should also have a condensing pressure that does not
exceed the pressure that the system components are designed for,
as this can have safety implications.
The capacity and COP are mainly dictated by the design and
control of the system itself (compressor, heat exchangers, piping,
etc), although the properties of the refrigerant play a part in this.
The COP can be affected by the compression ratio (which is
dictated by the saturation pressure-temperature characteristic), heat
exchanger performance and pressure losses around the system,
which are all influenced by latent heat, density, viscosity, thermal
conductivity, specific heat.
For a given evaporating and condensing temperature, the cooling
(or heating) capacity of a system is strongly influenced by the
latent heat and density of the gas entering the compressor. For
conventional systems, a fairly high critical temperature is preferred
(at least 20K above the condensing temperature), unless the
system is specially designed for operation near or above the critical
temperature, such as with R744 systems.
36

2
Refrigerants
Safety characteristics
CHAPITRE 2
PAGE 06
According to various international and national safety standards,
refrigerants may be allocated one of six safety classifications
Refrigerant are classified in terms of two general safety criteria: toxicity and
flammability.
according to its toxicity and flammability. This classification
consists of two alpha-numeric characters (e.g. A2); the capital letter
Toxicity: Both acute (short-term) and chronic (long-term) toxicity corresponds to toxicity and the digit to flammability. The toxicity
are considered as they affect human safety during handling and classification is determined by a refrigerants’ TLV-TWA, such that
servicing with refrigerants, and for occupants in refrigerated or air it may be lower toxicity “A” or higher toxicity “B”. There are no
conditioned spaces. The acute-toxicity exposure limit (ATEL) is refrigerants that are non-toxic.
the maximum recommended refrigerant concentration intended to
reduce the risks of acute toxicity hazards to humans in the event of
a refrigerant release. For chronic toxicity, the threshold limit value-
The flammability classification may be no flame propagation “1”,
lower flammability “2” or higher flammability “3”.
time weighted average (TLV-TWA) is the time -weighted average
concentration for a normal 8-hour workday
and a 40-hour workweek, to which nearly all
These classifications are shown in this table:
workers may be repeatedly exposed, day after
day, without adverse effect.
LOWER TOXITY HIGHER TOXITY
Flammability: Refrigerant flammability can
A3
affect the safety of people and property
mainly during handling and servicing activities,
A2
and it influences the design of equipment.
The flammability of a refrigerant is judged
A1
according to the lower flammability limit
(LFL), which is the lowest concentration of
the refrigerant mixed in air, required for it to
be able to be ignited. Flammability is also considered according to
the refrigerants’ heat of combustion (HOC), which is the amount of
energy released when it burns.
B3
B2
B1
HIGHER FLAMMABILITY
LOWER FLAMMABILITY
NO - FLAME PROPAGATION
Safety Classifications according to ISO 817, EN 378 and ASHRAE 34
standards
37

2
Refrigerants
Environmental parameters
Whenever a gas is released into the environment it has some
impact. The most important impacts related to refrigerants are
ozone depletion and global warming.
They are discussed in detail in
Chapter 1 4
Cost and availability
The cost (or retail price) of refrigerants varies widely, with HCFCs
tending to be cheaper, and HFC blends more expensive. Similarly,
the most widely used HCFCs (for example, R22) and the most
common HFCs (e.g. R134a) tend to be most widely available.
Hydrocarbon (HC) refrigerants tend to be less widely available, and
ammonia is normally sourced from specialist suppliers.
In reality, many of these parameters will already have been
addressed, for example, by refrigerant retailers, and through
the availability of components. Whilst there are several hundred
refrigerants currently available, this catalogue of products will have
been filtered down to a more manageable selection.
Most refrigerant retailers will stock around 20 different refrigerants,
whilst manufacturers of components (compressors, valves, heat
exchangers, etc) often limit their range to five to 10 refrigerants,
particularly for non-industrial applications. Often the predominant
selection criteria tend to be: the choice of operating pressures, safety
characteristics and whether the refrigerant has a high or low GWP.
In terms of selection for equipment servicing, the selection depends
upon whether the refrigerant currently in use is restricted or not.
If it is not restricted, then the same refrigerant as indicated on
the nameplate on the equipment should be chosen. If the named
refrigerant is restricted (i.e. due to it being unavailable because of
regulations), then a similar set of considerations need to be applied
as detailed above. The following section outlines the types of
refrigerants that are available.
38

2
Refrigerants
Types of refrigerants
Refrigerants can be divided in two main groups:
synthetic (basically halocarbon fluids: CFCs, HCFCs and HFCs) and
non-synthetic (hydrocarbons, carbon dioxide, ammonia, water, air –
so-called natural refrigerants).
Synthetic 4
Natural 4
39

2
Refrigerants
Synthetic refrigerants
Refrigerators from the late 1800s until 1929 used the higher
toxicity gases - ammonia, methyl chloride, and sulphur dioxide - as
refrigerants. Several fatal accidents occurred in the 1920s because
of methyl chloride leakage from refrigerators. A collaborative effort
began between three American corporations to search for a less
dangerous method of refrigeration.
In 1928, CFCs and HCFCs were invented as substitutes for the
higher toxicity and flammable refrigerants. CFCs and HCFCs
are a group of aliphatic organic compounds containing the
elements carbon and fluorine, and, in many cases, other halogens
(especially chlorine) and hydrogen. Most CFCs and HCFCs
tend to be colourless, odourless, non-flammable, non-corrosive
substances. Because CFCs and HCFCs have low toxicity, their
use eliminated the danger posed by refrigerator leaks. In just
a few years, compressor refrigerators using CFCs became the
standard for almost all home kitchens. In subsequent years, they
were introduced in a series of products, including R11, R113,
R114 and R22, that helped the expansion of the RAC industry
and applications. With the advent of the Montreal Protocol, HFC
refrigerants were developed during the 1980s and 1990s as
alternative refrigerants to CFCs and HCFCs.
Three groups could be considered:
Those with ozone depleting potential 4
Those without ozone depleting potential 4
Heat transfer fluids 4
More about the classification and use of different refrigerants:
Using Refrigerant Blends – issues and concepts 4
40

2
Refrigerants
Those with ozone depleting potential
Chlorofluorocarbons
CFCs consist of chlorine, fluorine, and carbon. The most common
refrigerants in this group are R11, R12 and R115 (within the blend
R502). As mentioned above, they have been in widespread use
since the 1930s, in nearly all applications, including domestic
refrigeration, commercial refrigeration, cold storage, transport
refrigeration and vehicle air conditioning. Because they contain
no hydrogen, CFCs are chemically very stable, and tend to have
good compatibility with most materials and traditional lubricants
such as mineral oils. Across the range of CFCs, they have a variety
of pressure-temperature characteristics, thus covering a fairly
wide range of applications. Their thermodynamic and transport
properties are generally good, thereby offering the potential for
good efficiency. Their good stability also results in lower toxicity and
non-flammability, thus usually achieving an A1 safety classification.
However, because they contain chlorine, CFCs are damaging to
the ozone layer (section 1), and due to their long atmospheric life,
the CFCs have a high ODP. Similarly, they are strong greenhouse
gases with high GWP. However, they are not controlled by the Kyoto
Protocol because they are controlled and are being eliminated by
the Montreal Protocol. Traditionally, CFCs have been very cheap
and widely available, although with their current phase-out, prices
will rise considerably and availability will lessen.
Hydrochlorofluorocarbons
HCFCs consist of hydrogen, chlorine, fluorine, and carbon. The
most common refrigerants in this group are R22, R123 and R124
(within various blends). As mentioned above, they have been in
widespread use since the 1930s, in nearly all applications, including
commercial refrigeration, cold storage, transport refrigeration,
stationary air conditioning and chillers. Because they contain
hydrogen, HCFCs are theoretically less chemically stable than
CFCs, but nevertheless tend to have good compatibility with most
materials and traditional lubricants such as mineral oils. Across
the range of HCFCs, there are a variety of pressure-temperature
characteristics. Their thermodynamic and transport properties are
typically very good, thereby offering the potential for very good
efficiency. Although some HCFCs have an A1 safety classification,
due to their less stable nature, some HCFCs have A2 (low-toxicity,
lower-flammability) and B1 (higher toxicity, non-flammable) safety
classifications. As with CFCs, because of the chlorine content,
they are damaging to the ozone layer (Chapter 1), although with
a relatively low ODP. Similarly, they are strong greenhouse gases
with high GWP. Again, they are not controlled by the Kyoto Protocol
because they are controlled and are being eliminated by the
Montreal Protocol. Currently, HCFCs are very cheap and widely
available, although with the forthcoming accelerated phase-out,
prices will rise considerably and availability will lessen.
41

2
Refrigerants
Hydrofluorocabons (HFCs)
HFCs consist of hydrogen, fluorine, and carbon. The most common
refrigerants in this group are R134a, R32, R125 and R143a (mostly
within blends, such as R404A, R407C and R410A). They have been
in large scale use since the 1990s, in nearly all applications that
have traditionally used CFCs and HCFCs, including domestic and
commercial refrigeration, cold storage, vehicle air conditioning,
transport refrigeration, stationary air conditioning and chillers.
HFCs are generally chemically very stable, and tend to have good
compatibility with most materials. However, they are not miscible
with traditional lubricants, so other types of synthetic oils must be
used. Across the range of HFCs, there are a variety of pressuretemperature
characteristics. Their thermodynamic and transport
properties range from fairly to very good, thereby offering the
potential for good efficiency. Although some HFCs have an A1 safety
classification, some have A2 (low-toxicity, lower-flammability) safety
classifications. Unlike CFCs and HCFCs, they contain no chlorine,
and are thus not damaging to the ozone layer (Chapter 1). However,
due to their long atmospheric lifetime, they are typically strong
greenhouse gases with high GWP. They are controlled by the Kyoto
Protocol. Currently, HFCs carry a moderate price, with the blends
being more expensive. Although numerous countries are developing
legislation to control the use and/or emissions of HFCs, many are
widely available, and will continue to be so for the foreseeable future.
Those without ozone depleting potential 4
Heat transfer fluids 4
Using Refrigerant Blends – issues and concepts 4
42

2
Refrigerants
Those with zero ozone depleting potential
There are three other sub-categories of synthetic refrigerants that have zero
ODP and play a part in RAC:
Perfluorocarbons
They represent another group of fluorocarbons which contains
five different fluids. One of these (R218) is occasionally used in
refrigerant blends. Generally PFCs are very stable, but as a result
have very high GWP.
Unsaturated HFCs
Whilst conventional HFCs are saturated, there are a small number
of unsaturated HFCs, known as olefins. Generally, there are highly
unstable, but recently a small number have been identified which
are sufficiently stable to be used as refrigerants, and have lowtoxicity
and low flammability and low GWP. The two receiving most
interest are R1234yf and R1234ze; the former is being considered
for use in MVAC systems, but it is unlikely that they will be applied
as refrigerant in other sectors for several years.
Hydrofluoroethers
This group of fluorinated chemicals tends to be fairly stable and
amongst them have a fairly wide range of boiling points, although
they tend to be lower pressure fluids. They have been considered
as use as refrigerants, but to date have not achieved market
acceptance for various reasons.
Those with ozone depleting potential 4
Heat transfer fluids 4
Using Refrigerant Blends – issues and concepts 4
43

2
Refrigerants
Natural refrigerants
Various hydrocarbons, ammonia and carbon dioxide belong to a group
named “natural refrigerants”. All natural refrigerants exist in material cycles
present in the nature even without human interference. They have zero ODP
and zero or negligible GWP. Evolutions and technological innovations have
helped in the consideration of “natural refrigerants” as a safe and economic
solution for applications in many sectors. Because of minimal environmental
impacts and for being more appropriated in a sustainable technological
development perspective, refrigeration systems with natural refrigerants
could have an important role in the future in many applications.
Ammonia (NH3, R717)
Ammonia contains nitrogen and hydrogen, and is widely used
within many industries. It has been used widely as a refrigerant
since the late 1800’s, and is currently in common use in industrial
refrigeration, cold storage and food process cooling, and
more recently is being used for commercial refrigeration and
chillers. R717 is chemically stable, but will react under certain
conditions, for example when it is in contact with carbon dioxide,
or water and copper. Otherwise, compatibility in steel systems
and correctly chosen oils is good. The pressure-temperature
characteristic of R717 is broadly similar to that of R22. However,
it’s thermodynamic and transport properties are excellent, leading
to potentially highly efficient systems. Due to its higher toxicity
and lower flammability, it has a B2 safety classification. Unlike the
fluorinated gases, it has no impact on the ozone layer and has a
zero GWP, so it is controlled by neither the Kyoto Protocol nor the
Montreal Protocol. R717 is very cheap and widely available from
specialist retailers.
Hydrocarbons (HCs)
Hydrocarbons contain hydrogen and carbon, and are widely used
within many industries. The most commonly used for refrigeration
purposes are isobutane (C4H12, R600a) and propane (C3H8,
R290), propylene (C3H6, R1270), and blends thereof. Within
industrial applications, a variety of other HCs are widely used.
In general, HCs had been widely used a refrigerant since the
late 1800s until 1930s, and has been re-applied since the early
1990s. Apart from industrial applications, HCs have been used in
domestic refrigeration, commercial refrigeration, air conditioners
and chillers. HCs are chemically stable, and exhibit similar
compatibility to the CFCs and HCFCs. Across the range of HCs,
there are a variety of pressure-temperature characteristics. They
also have excellent thermodynamic and transport properties,
leading to potentially very efficient systems. Due to their higher
flammability, all HCs have an A3 safety classification. As with
R717, they have no impact on the ozone layer and have a
negligible GWP, so are controlled by neither the Kyoto Protocol
nor the Montreal Protocol. R600a and R290 are fairly cheap but
availability is disparate, depending upon the country.
44

2
Refrigerants
Carbon dioxide (CO2, R744)
Carbon dioxide contains carbon and oxygen, and is widely used
within many industries. It had been extensively applied as a
refrigerant since the mid-1800s, but this also ceased with the
advent of the CFCs and HCFCs. From the later 1990s, its has reemerged
as a refrigerant and its use is currently increasing within
industrial refrigeration, cold storage, commercial refrigeration and
hot-water heat pumps, amongst others. R744 is chemically stable,
and does not react under most conditions, and is compatible
with many materials. The pressure-temperature characteristic of
R744 are different from most conventional refrigerants, in that it
operates at pressures, for example, approximately seven times
higher than R22, which necessitates the system to be designed with
special consideration to high pressures. In addition, it has a low
critical temperature, such that when ambient temperatures exceed
about +25°C, a special system design is required. Otherwise, it’s
thermodynamic and transport properties are excellent, leading
to potentially highly efficient systems within cooler climates. Due
to its lower toxicity and non-flammability, it has an A1 safety
classification. Unlike the fluorinated gases, it has no impact on the
ozone layer so is not controlled by the Montreal Protocol. However,
despite it having a GWP of 1, it is included within the Kyoto
Protocol, but its use it not restricted as a result of this. R744 is very
cheap and widely available from specialist retailers.
Refrigerant numbering
Chemical names of typical refrigerants are generally long and
complex. In order to create a more simple way to designated
refrigerants a method of identifying them by number was
developed. IIR’s note on classification of refrigerants that describes
the basic rules for adopting the number of the refrigerant (see
www.iifiir.org/en/doc/1034.pdf). The classification is based on the
standard ASHRAE 34 and makes it possible to name all refrigerants
used in a clear and internationally recognised way by classifying
them according to their chemical composition. Basically an
identifying number is assigned to each refrigerant. It consists of a
prefix made up of letters and a suffix made up of digits. The prefix
is composed of the letter R (for refrigerant). Examples: R22, R134a,
R600a, R717. Blended refrigerants, whether they are zeotropic or
azeotropic, always being with R4xx or R5xx, respectively.
Refrigerant blends characteristics and pros and cons:
Lubricants properties and choices:
Refrigerant blends 4
Lubricants 4
Once you have explored these characteristics the next button introduces
refrigerants and their appropriate use:
Using Refrigerant Blends 4
45

2
Refrigerants
Refrigerant blends
Although refrigerants can be one single substance, they can also
be a mixture of two or more substances, and these are normally
referred to as “blends”. Refrigerant blends have been formulated
to provide a match to certain properties and characteristics of
the refrigerants originally used (i.e. in the case of retrofit blends),
or to achieve a particular set of properties for other reasons.
Most commercially available blends have between two and five
components. These components may be HCFCs, HFCs and/or
HCs and PFCs. The individual component refrigerants in a blended
refrigerant do not have identical physical characteristics; they have
different densities, different viscosities and different evaporation and
condensation temperatures at a given pressure. With most blends,
the components within the mixture change their composition in the
liquid and vapour phases as the blend boils or condenses; these
are known as zeotropes. These have an R-number designation,
R4xx. Less commonly, the individual components in certain blends
interact such that the vapour phase and liquid phase have the same
composition at a given pressure; these blends are called azeotropic
mixtures. These have an R-number designation, R5xx.
There are two types of blend:
Azeotropic 4
Zeotropic 4
46

2
Refrigerants
Azeotropic Blends
An azeotropic blend is a mixture of usually two substances, which
behaves as if it were a pure fluid. When heat is added to or removed
from an azeotropic refrigerant blend, the composition (mole
fraction) of the vapour and the liquid remain essentially unchanged
throughout the complete process. In other words, in a blend of
50% of fluid A and 50% of fluid B, for every molecule of fluid A that
vaporises or condenses, a molecule of fluid B does the same.
An azeotropic blend behaves like a single refrigerant when condensing or
evaporating, i.e., the temperature remains constant at a given pressure, as
shown in this figure:
TEMPERATURE
SINGLE COMPONENT
PRESSURE - TEMPERATURE CHART
LENGTH OF HEAT EXCHANGER
SUBCOOLED
SUPERHEATED
BOILING
EVAPORATING
EVAPORATING
(CONSTANT PRESSURE)
Condensation
and evaporation of
an azeotropic blend
Historically, the commonly used ozone depleting substance (ODS)
blends were R500 (mixture of R12 and R152a) and R502 (mixture of
R22 and R115). More recently, an azeotropic blend using only HFCs
has been found, R507A (mixture of R125 and R143a).
Zeotropic blends
A zeotropic blend is a mixture of refrigerants whose different
volatilities are seen when observing the performance of a
refrigeration cycle. For example, a change in the molar composition
and/or a change in saturation temperature during boiling or
condensation; in this way, it does not behave like a single refrigerant
when condensing or evaporating.
Two different situations arise, depending upon the type of system.
Direct expansion system:
• Flow-boiling occurs in the evaporator and flow-condensation in
the condenser. Fluid A boils or condenses at a different rate than
fluid B, and because the liquid composition of fluid A and fluid
B changes, whilst the pressure remains the same, the saturation
temperature along the heat exchanger varies.
• Flooded system: Pool-boiling occurs in the evaporator and filmcondensation
in the condenser. Fluid A boils or condenses at a
different rate from fluid B, which results in an accumulation of
the most volatile fluid in the condenser and the less volatile fluid
in the evaporator. Whilst the phase-change process occurs at
a constant temperature, there is essentially a short-circuiting of
the refrigerant, which results in a loss in performance.
47

2
CHAPITRE The 2 next illustration shows action of a zeotropic mixture of
PAGE 16
refrigerant components, fluid A and fluid B, as it flows through a
heat exchanger tube. In the case of a pure fluid, the temperature
of the refrigerant remains the same as the liquid vaporises, or
the vapour condenses. However, with a zeotropic blend, as the
refrigerant vaporises, the saturation temperature rises, or as the
vapour condenses, the saturation temperature falls. The refrigerant
is at the bubble temperature when it is just a pure liquid (e.g. when
it is just evaporating) and is at the dew temperature when it is just a
pure gas (e.g. when it is just condensing).
Refrigerants
The range of temperature between the dew point and bubble point is called
the temperature glide. This is illustrated here:
TEMPERATURE
EVAPORATION
LIQUID VAPOUR
CONDENSATION
PROPORTION VAPORISED/CONDENSED
Behaviour of a zeotropic blend with changing temperature
PURE FLUID A
BLEND OF FLUID
A AND FLUID B
PURE FLUID B
DONE
TEMPERATURE
ZEOTROPIC BLEND
PRESSURE - TEMPERATURE
CHART
LENGTH OF HEAT EXCHANGER
GLIDE
BUBBLE POINT
(LIQUID WITH A
«BUBBLE» IN IT)
SUBCOOLED
BOILING
DEW POINT
(VAPOR WITH A
«DEW DROP» IN IT)
Condensation and evaporation of a zeotropic blend
Prior to the Montreal Protocol, zeotropic mixtures were
rarely used, perhaps the only example being R400 (a
mixture of R12 and R114). In the search for alternatives
for CFCs, and latterly, for alternatives for HCFCs, a large
number of zeotropic mixtures have been formulated. Some
of the HFC and HC based zeotropic blends to replace
CFCs and HCFCs are: R404A, R407C, R410A and R436B.
48

2
Refrigerants
Using Refrigerant Blends – issues
and concepts
The following graphic allows you to consider different concepts and issues
relating to the use of refrigerant blends.
Temperature glide 4
Composition 4
Flammability 4
When considering these factors combined there are pros and cons for blends.
Pros and cons for blends 4
Temperature glide
The characteristic called “temperature glide” refers to the
temperature range over which components in a blended refrigerant
boil or condense at a given pressure. A pure substance (like water)
at a constant pressure will go through a complete phase change at
a constant temperature. Conversely, a zeotropic blended refrigerant
must proceed through a temperature range in order to complete the
phase change process. The name temperature glide refers to this
range of temperature. Similarly, if a zeotropic refrigerant was left
to boil off within a bucket, the temperature at which it would start
to boil would be the bubble-point temperature, and eventually the
last few drops would be boiling off at the dew-point temperature.
However boiling and condensation in “flooded” type evaporators
and condensers will not normally exhibit any temperature glide
because they are constantly being replenished with new refrigerant.
Thus the refrigerant is seen to change phase at a single temperature
- the bubble-point in an evaporator and dew-point in a condenser.
Composition
The specific characteristic of zeotropic blends, i.e., the liquid and
vapour composition, is different at most given temperature and
pressure. This causes concerns relating to composition changes in
the refrigerant supply chain, including liquid removal from containers
for multi-component refrigerant mixtures in the manufacturer plant,
and refrigerant transfers to smaller containers by dealers. A study
conducted by the Air Conditioning and Refrigeration Institute (ARI) in
USA indicates “refrigerant mixtures can have composition changes
during the handling procedures that lead to out-of-specification
composition”. The refrigerant transfer and equipment charging by
technicians, and refrigerant equipment leakage could also change
the composition. The change of the composition will affect the
performance to some extent. Accordingly, ARI and Deutsches Institute
für Normung (DIN) sets composition tolerances for specific blends, for
example, ARI composition tolerances for R410A (R32/R125) are +0.5,
-1.5% for R32, and +1.5, -0.5% for R125.
49

2
Refrigerants
Flammability
Several of the blends use flammable refrigerants as one of the
components, and some blends just use a mixture of hydrocarbons.
Therefore, some safety concerns are raised for their application.
Some regions and countries set a limitation in specific equipment
for such kinds of blends or even forbid their use. In developed
countries, the HCFC based blends for replacement of R12 were not
widely used for the manufacturing of new equipment or retrofitting
of existing equipment partly due to its ODP value, flammability and
servicing complications. Also, the retrofitting of appliances is not
practiced in developed countries mainly because of the availability
of recycled CFC for servicing and high retrofitting cost due to higher
labour charges compared to new equipment cost.
Pros and Cons of refrigerant blends
Pros of refrigerant blends:
• The refrigerant blends provide another way to assist the country in
complying with the CFCs phase-out provision under the Montreal
Protocol whilst not harming the interests of the end users.
• The refrigerant blends (if the main components are either R22/
R152a/HCs) can be cheaper than R134a and other alternatives;
they tend to be widely available.
• The HCFC based refrigerant blends as mentioned above aimed
to replace R12 can mostly be used with mineral oils and can
provide acceptable performance in retrofitted equipment.
Cons of refrigerant blends:
• HCFC-based blends are an interim CFC replacement solution.
• Due to the non-azeotropic and possible flammable characteristics,
the servicing procedure especially charging would be complicated
and the technicians should be informed to follow proper handling
procedures.
• It is more difficult to estimate the amount of superheat and subcooling
when commissioning or servicing a system.
• Leakage from heat exchangers and subsequent re-filling will
lead to a gradual change in composition, thereby resulting in a
change in performance and operating characteristics over time.
• The introduction of more refrigerants in the market might
confuse the technicians, causing more cases of crosscontamination
in running the refrigeration system.
• Even though the short-term impact on the performance of the
equipment might not be noticed by the equipment owner, it is
believed the cross-contamination of a refrigerant/lubricant will
reduce the equipment’s energy efficiency and its performance,
and shorten the operational life of the equipment.
• More blends will also complicate the recovery/recycling
programme due to the cross-contamination, as equipment with
the blends might not be properly labelled or the technicians may
just ignore the label.
• Some blends are advertised to replace R134a, so it might cause
backward retrofitting from R134a to HCFC-based blends.
50

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Refrigerants
Lubricants
Today, almost as many new lubricants are on the market as there are
refrigerants. Compressor manufacturers always specify oil type and
fill each model of compressor accordingly. One of the most common
mistakes whilst servicing is not checking which is the appropriate
lubricant for the serviced system; this could cause damage to
the system due to non-compatibility with refrigerant and system
components. In hermetic systems, the lubricant is in intimate contact
with the electrical motor windings. The oil must therefore provide
good, material compatibility and have high thermal stability properties.
Although the majority of the lubricant remains in the compressor, a
small amount will be circulated into the rest of the refrigerant circuit.
The lubricant must be able to resist both the high temperatures at
the compressor discharge valves and the low temperatures at the
expansion device. It must be sufficiently soluble with the refrigerant
itself in order for it to be returned back to the compressor, so that
over time, it does not become starved of oil, which could lead to
mechanical failure. There properties are discussed next.
Properties
The properties of a good refrigeration lubricant are:
• Low wax content. Separation of wax from the refrigeration oil
mixture may plug refrigerant control orifices
• Good thermal stability. It should not form hard carbon deposits
and spots in the compressor, such as in the valves of the
discharge port
• Good chemical stability. There should be little or no chemical reaction
with the refrigerant or materials normally found in systems
• Low pour point. This is the ability of the oil to remain in a fluid
state at the lowest temperature in the system
• Good miscibility and solubility. Good miscibility ensures that the oil
will be returned to the compressor, although a too high solubility
may result in lubricant being washed off the moving parts
• Low viscosity index. This is the ability of the lubricant to maintain
good oiling properties at high temperatures and good fluidity at low
temperatures and to provide a good lubricating film at all times.
Categories
Basically there are six main categories of refrigeration lubricants:
• mineral oils (MO)
• alkyl benzene oils (AB)
• polyol ester oils (POE)
• poly alpha olefin oils (PAO)
• poly alkyl glycol oils (PAG)
Traditionally, CFC refrigerants have been used with mineral and
alkyl benzene oils for the lubrication of compressors. This is now
undergoing change, with the introduction of HFC refrigerants, which
are immiscible with the traditional mineral oils, and need the use of
synthetic oils for miscibility and oil return.
51

2
Refrigerants
Characteristics
An important characteristic of many of the synthetic lubricants,
such as POE and PAG oils, is that they are more hygroscopic
than mineral oils as shown in the diagram below. They saturate at
approximately 1000 ppm from atmospheric moisture, compared to
about 100 ppm for mineral oils. The POE lubricants are considerably
less hygroscopic than PAG lubricants. This diagram shows lubricant
compatibility for some refrigerants.
MOISTURE CONTENT
TIME (HOURS)
Hygroscopy of POE and mineral lubricants
PAG
POE
MINERAL
10 000 PPM
1000 PPM
100 PPM
Refrigerant Mineral
Oil (MO)
Alkyl
benzene
(AB)
Appropriate Lubricant
Polyol
Ester
(POE)
Poly alpha
oelfin
(PAO)
Chapter 4 of this manual presents information about the problems moisture
can create in a system, and how to deal with them.
52
Poly alkyl
glycol
(PAG)
CFC-11 � � � � �
CFC-12 � � � � �
R-502 � � � � �
HCFC-22 � � � � �
HCFC-123 � � � � �
HFC-134a � � � � �
HFC-404A � � � � �
HFC-407C � � � � �
HFC-410A � � � � �
HFC-507A � � � � �
HC-600a � � � � �
HC-290 � � � � �
R-717 (NH 3 ) � � � � �
R-744 (CO 2 ) � � � � �
�: Good Suitability �: Application with limitations �: Not Suitable

2
Refrigerants
Refrigerants and applications
Application
Domestic
refrigeration
Stand alone
retail food
display and
vending
Condensing
Units
Large
Supermarket
Systems
Cold Storage
Traditional
refrigerants
R12
R12
R22, R502
R502
R22
R502
R502
R22
R717
Retrofit / drop-in refrigerants
Transitional Longer term
R401A, R401C,
R405A, R406A,
R414A, R414B,
R415B
R401A, R401C,
R405A, R406A,
R409A (HT), R414A,
R414B, R415B,
R416A (HT), R420A
(HT)
R408A (HT), R411A,
R411B, R412A,
R415A, R418A
R408A (HT), R411A,
R411B, R412A,
R415A, R418A
R408A (HT), R411A,
R411B, R412A,
R415A, R418A
R408A (HT), R411A,
R411B, R412A,
R415A, R418A
R426A, R430A,
R435A, R436A*,
R436B*, R437A
R426A, R429A (HT),
R430A, R435A,
R436A*, R436B*,
R437A (LT)
R290*, R417A,
R419A (HT), R422B,
R422D, R424A,
R431A, R438A
R417A, R419A (HT),
R422B, R422D,
R424A, R431A,
R438A
R417A, R419A (HT),
R422B, R422D,
R424A, R431A,
R438A
R417A, R419A (HT),
R422B, R422D,
R424A, R431A,
R438A
New system refrigerants
R134a, R600a*
R600a*, R134a, R423A, R435A,
R436A*, R436B*, R510A
R290*, R404A, R407A/B/D/E,
R421A, R421B, R427A,
R433A/B/C, R507A, R744
R404A, R407A/B/D/E, R421A,
R421B, R427A, R433A/B/C,
R507A, R744
R404A, R407A/B/D/E, R421A,
R421B, R427A, R433A/B/C,
R507A, R744, Indirect systems
(using R290*, R1270*, R717*)
R404A, R407A/B/D/E, R421A,
R421B, R427A, R433A/B/C,
R507A, R744, Indirect systems
(using R290*, R1270*), R717*
The chart presents an overview of main alternative
refrigerants to CFCs and HCFCs in diverse RAC applications.
For each application, there are four lists of refrigerants:
• Traditional refrigerants, what would usually have been
used prior to the Montreal Protocol.
• Retrofit / drop-in refrigerants, are refrigerants that have
been developed, or can be used in existing systems
that contained the traditional refrigerants, and
typically contain some HC component so that they
are soluble with existing mineral oils.
These have been divided into two further categories:
• Transitional refrigerants that comprise some HCFCs,
and are therefore still controlled by the Montreal
Protocol, and should only considered for short-term
use in systems that contained CFCs.
• Long-term refrigerants that do not comprise any
ozone depleting substances, and can be considered
to be unrestricted.
• New system refrigerants, which include refrigerants
that are also not restricted by the Montreal Protocol
and are expected to be applicable for the long term.
53

2
Refrigerants
Application
Industrial
Process
Refrigeration
Refrigerated
Transport
Split and
ducted air
conditioners
Portable and
window
Application
units
Heat Pumps
Chillers
Mobile air
conditioning
(MAC)
Traditional
refrigerants
R22
R502
R717
R290/
R1270
R12
R502, R22
R22
R22 Traditional
refrigerants
R22
R11
R123
R12
R22
R12
Retrofit / drop-in refrigerants
Transitional Longer term
R408A (HT), R411A,
R411B, R412A,
R415A, R418A
R401A, R401C,
R405A, R406A,
R409A (HT), R414A,
R414B, R415B,
R416A (HT), R420A
(HT)
R408A (HT), R411A,
R411B, R412A,
R415A, R418A
R408A, R411A,
R411B, R412A,
R415A, R418A
R417A, R419A (HT),
R422B, R422D,
R424A, R431A,
R438A
R426A, R429A (HT),
R430A, R435A,
R436A*, R436B*,
R437A (LT)
R290*,R417A,
R419A (HT), R422B,
R422D, R424A,
R431A, R438A
R290*,R417A,
R419A, R422B,
R422D, R424A,
R431A, R438A
R290*,R417A,
R408A, R411A,
R411B, R412A,
Retrofit / drop-in R419A, refrigerants R422B,
R422D, R424A,
R415A, R418A
Transitional R431A, Longer R438A term
R408A, R411A,
R411B, R412A,
R415A, R418A
R290*,R417A,
R419A, R422B,
R422D, R424A,
R431A, R438A
New system refrigerants
R404A, R407A/B/D/E, R421A,
R421B, R427A, R433A/B/C,
R507A, R744, Indirect systems
(using R290*, R1270*), R717*
R134a, R423A, R435A, R436A*,
R436B*, R510A*
R404A, R407A/B/D/E, R421A,
R421B, R427A, R433A/B/C,
R507A, R744, R290*, R1270*
R407A/C/D/E, R421A, R427A,
R433A/B/C, R290*, R1270*, R410A
R407A/C/D/E, R421A, R427A,
New R433A/B/C, system refrigerants R290*, R1270*, R410A
R407A/C/D/E, R421A, R427A,
R433A/B/C, R744, R290*, R1270*,
R410A
None None R236ea, R236fa, R245fa
R401A, R401C,
R405A, R406A,
R409A, R414A,
R414B, R415B,
R416A, R420A
R408A, R411A,
R411B, R412A,
R415A, R418A
R401A, R401C,
R405A, R406A,
R409A, R414A,
R414B, R415B,
R416A, R420A
R426A, R429A,
R430A, R435A
R290*,R417A,
R419A, R422B,
R422D, R424A,
R431A, R438A
R426A, R429A,
R430A, R435A,
R436A*, R436B*
R134a, R423A, R435A
R407A/C/D/E, R421A, R427A,
R433A/B/C, R744, R290*, R1270*,
R410A
R134a, R744
A number of additional observations are made:
• Many of the blends in the “longer term” and “new
system” lists contain HFCs and PFCs, which are
included in the Kyoto Protocol, and are being
legislated against in several European counties.
• Flammable refrigerants – indicated with an asterisk (*)
must be handled appropriately, that is, systems are
designed and maintained according to safety rules. If
they are used as a drop-in refrigerant, the technician
must ensure that the conversion has been done
according to the appropriate safety rules.
• The initials “(HT)” and “(LT)” imply that the refrigerant
is more suited to high temperature (eg, chilled food) or
low temperature (eg. frozen food), respectively.
• In addition to the refrigerants listed, there are many
other products on the market that do not have an
R-number. Similarly, many of the refrigerants listed
are marketed under trade names, rather than the
R-number.
• Systems using carbon dioxide systems need to be
designed with particular respect to its thermodynamic
characteristics.
54

2
Refrigerants
Properties of most common refrigerants
These are properties of refrigerants mostly used:
Refrigerant Chemical
type
Molecular
mass
NBP (°C)
Pressure at
35°C (kPa)
Critical Safety
temp (°C) class
ODP
(MP)
R11 CFC 137.7 23.7 149 198 Al 1 4750
GWP
(100)
R12 CFC 120.9 -29.8 846 112 Al 1 10890
R22 HCFC 86.4 -40.8 1355 96.1 Al 0.055 1810
R114 CFC 170.9 3.6 292 145.7 Al 1 10040
R123 HCFC 152.9 27.8 131 183.7 Bl 0.02 77
R134a HFC 102.0 -26.1 887 101.1 Al 0 1430
R152a HFC 66.1 -24 794 113.3 A2 0 124
R290 HC 44.1 -42.1 1218 96.7 A3 0 3
R401A HCFC/HFC 94.4 -32.9 961 107.3 Al 0.04 1180
R401B HCFC/HFC 92.8 -34.5 1024 105.6 Al 0.04 1290
R402A
R402B
R403A
R403B
HCFC/HFC/
101.6 -48.9 1733 75.8 Al 0.02 2790
HC
HCFC/HFC/
94.7 -47 1635 82.9 Al 0.03 2420
HC
HCFC/PFC/
HC
HCFC/PFC/
HC
92.0 -47.7 1649 87 Al 0.04 3120
103.3 -49.2 1715 79.6 Al 0.03 4460
Refrigerant Chemical
type
Molecular
mass
NBP (°C)
Pressure at
35°C (kPa)
Critical Safety
temp (°C) class
55
ODP
(MP)
R404A HFC 97.6 -46.2 1629 72 Al 0 3920
R407C HFC 86.2 -43.6 1414 86 Al 0 1770
R409A HCFC 97.4 -34.4 977 109.3 Al 0.05 1590
R409B HCFC 96.7 -35.6 1024 106.9 Al 0.05 1560
R410A HFC 72.6 -51.4 2071 71.4 Al 0 2090
R413A
PFC/HFC/H
C
GWP
(100)
104.0 -33.4 1067 96.6 A2 0 2050
R417A HFC/HC 106.8 -39.1 1315 87.1 Al 0 2350
R500 CFC/HFC 99.3 -33.6 980 102.1 Al 0.74 8070
R502 CFC/HCFC 111.6 -45.3 1464 81.5 Al 0.33 4660
R600a HC 58.1 -11.7 465 134.7 A3 0 4
R717 NH3 17.0 -33.3 1351 132.3 B2 0 0
R744 CO2 44.0 -54.4 >7300 31 Al 0 1
R1270 HC 42.1 -47.6 1469 91.1 A3 0 2

2
Refrigerants
Further reading
US Environmental Protection Agency - Significant New Alternatives Policy (SNAP) Program
4 www.epa.gov/ozone/snap/index.html
UNEP DTIE OzonAction - Fact Sheet No. 16 on Refrigerant Blends
4 www.uneptie.org/ozonaction/information/mmcfiles/4766-e-16blends.pdf
UNEP DTIE OzonAction - HCFC Help Centre : Refrigerant blends containing HCFCs,
UNEP
4 www.uneptie.org/ozonaction/topics/hcfcblends.htm
UNEP DTIE OzonAction – Refrigeration & Air-Conditioning
4 http://www.uneptie.org/ozonAction/topics/refrigerant.htm
UNEP DTIE OzonAction – Protecting the Ozone Layer, Volume 1, Refrigerants,
UNEP, 2001
4 www.unep.fr/ozonaction/information/mmcfiles/2333-e.pdf
International Institute of Refrigeration – Classification of Refrigerants based on
American standard ANSI/ASHRAE 34 published in 2001
4 www.iifiir.org/en/doc/1034.pdf
Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Proklima - Natural Refrigerants:
Sustainable Ozone- and Climate-Friendly Alternatives to HCFCs, GTZ Proklima, 2008
4 http://www.gtz.de/de/dokumente/en-gtz-proklima-natural-refrigerants.pdf
or
4 www.gtz.de/en/themen/umwelt-infrastruktur/23898.htm
56

3
Refrigerants Content
Management Management plans 4
Handling of refrigerants 4
Refrigerant cylinders 4
Management: Cylinder inspections and re-testing 4
Refrigerant recovery and recycling 4
Identification and testing of refrigerants 4
Recognising Refrigerant cylinder colour codes 4
Examples of refrigerant recovery 4
Further reading 4

3
Summary 3.1. Management plans
This chapter covers a variety of important aspects
related to the handling and management of
refrigerants, with the primary focus on maintaining
good quality refrigerant and avoiding emissions and
wastage. Specific topics include: the good handling
and use of cylinders, and issues related to the re-use
and proper disposal of refrigerants. In addition, the
concept of refrigerant conservation is explained, with
practical measures for all stages of refrigerant use,
such as containment within systems, proper recovery
and recycling methods and reclamation. The reader
should be able to:
• Describe how to correctly handle refrigerants
• Describe the ways to promote refrigerant
conservation
• Identify refrigerant emissions
• Describe how to perform refrigerant recovery and
recycling activities
Refrigerant Management
Refrigerant management has been done in two levels: at a country government
level and at installation/application level. Strategies for refrigerant
management have been developed at a country level as an action
of the Montreal Protocol implementation in developing countries by
UNEP and other implementing agencies in conjunction with National
Ozone Units (NOUs) and other governmental institutions.
The Multilateral Fund (MLF) assistance to Article 5 countries in
the refrigeration servicing sector started in 1991 when projects
for training service technicians and recovering and recycling
chlorofluorocarbon (CFC) refrigerants were first approved. In 1997 these
standalone projects were replaced by Refrigerant Management Plans
(RMP). Refrigerant management is an approach to optimising the
use of available refrigerants in the existing equipment and minimising
the demand for virgin refrigerants for servicing through technical and
regulatory measures. This is aiming to allow the appropriate operation
of the equipment throughout its lifecycle at reducing harmful impact
to the environment resulting from the emission of refrigerants.
The conditions and resources allocated for the RMPs have been
adjusted from time to time. After the RMPs, projects called Terminal
Phase-out Management Plans (TPMP) have been developed. Under
a TPMP, a country receives funding for a full phase-out of CFC
consumption on the understanding that no further funding will be
requested.

3
Refrigerant Management
The majority of the RMPs and TPMPs are carried out in lowvolume
consuming countries (LVC) with 75%–100% of the CFCs
consumption in the servicing sector. Since 2007 with the approval
of the acceleration of the phase-out of hydrochlorofluorocarbons
(HCFCs), the Multilateral Fund for the Implementation of the
Montreal Protocol is supporting the development of HCFC phaseout
management plans (HPMPs) in developing countries.
Refrigerant management plans for CFCs (RMP)
An RMP is a comprehensive strategy to phase out the use of ozone
depleting refrigerants used to service and maintain refrigeration
and air conditioning systems. It may include actions to reduce ODS
consumption and emissions, reduce the need for further servicing
by controlling new installations and restricting imports of equipment
that depend on ODS for their functioning, and promote retrofitting
and replacement of existing equipment. Regulations, economic
incentives and disincentives, training, and public awareness
activities are some of the tools used to achieve these goals.
The successful implementation of RMPs requires the coordination of
activities in different ODS-using sectors, including:
• Manufacturing
• Servicing
• End-users sectors
• Regulatory and trade controls
• Economic incentives and disincentives
• Training on good practices in refrigeration for service technicians
• Training for customs officers
• Establishing recovery and recycling programmes
• Public awareness campaign.
Terminal phase-out management plan for CFCs (TPMP)
The TPMP contains the Compliance Strategy and Action Plan for
the elimination of the use of the CFCs controlled under Annex A
Group I of the Montreal Protocol, until their final phase out on 1st
January 2010. It also contains follow up actions, to ensure the
necessary compliance monitoring and reporting.
HCFC phase-out management plan (HPMP)
The HPMP includes undertaking a comprehensive survey of the
refrigeration and air conditioning sector and all sectors and subsectors
that use HCFC. It describes the overall strategy that will be
followed by the country to meet the complete phase-out of HCFCs.
This includes policy instruments to reduce supply of HCFCs, and
a plan for implementation of alternatives for new and existing
equipment and products. The HPMP needs to take into account the
climate impact of the alternatives, and should be coordinated with
chemical management and energy policies.
59

3
Refrigerant Management
To implement a strategy for refrigerant management in a
country, it is essential to develop actions at field installations
level. Technicians in developing countries have a very
important role helping their countries to implement plans to
phase-out CFC and HCFC refrigerants, and also to decrease
emissions of hydrofluorocarbon (HFC) refrigerants.
This can only be achieved with the adoption of good practices
in refrigerant management, in handling and working with
refrigerants. This is the role of refrigeration and air conditioning
(RAC) technicians, and this is the focus of this manual.
In the end, one can say that we
should apply to refrigerants a general
concept that starts to be used
in waste management is the 4R
principle: Reduce the use, Recovery,
Recycling and Reuse. This can
be achieved through technology
development, making systems more
hermetic and with lower refrigerant
charge and through good practices
on refrigerant management. The last
is refrigeration technicians’ task and
this section provides some guidance
on that. We start with handling of
refrigerants.
60

3
Refrigerant Management
Handling of refrigerants
Below are presented some aspects of the management of refrigerant
cylinders. Specific considerations about safety and care precautions
concerning the manipulation and direct contact with refrigerant itself are
presented in
Chapter 6 4
Refrigerant cylinders
Refrigerants are packed in both disposable and returnable (refillable)
shipping containers, commonly called “cylinders”. Disposables
are manufactured in sizes from 0.5 litres to 22 litres capacity
(corresponding to approximately 0.5 to 25 kg of CFC, HCFC or
HFC refrigerant). They are considered pressure vessels, and in most
countries therefore are subject to national regulations.
Containers are designed for pressurised and liquefied gases,
and are labelled accordingly. Some refrigerants are gases at
atmospheric pressure and room temperature, and are therefore
transported and stored as liquefied compressed gases in
pressurised cylinders. Other refrigerants are liquids at room
temperature and contained in drums, barrels or other standard
containers.
Numerous regulations are in force worldwide for the manufacture,
handling and maintenance of pressurised containers. Cylinders are
manufactured to specifications established by countries regulatory
authorities.
There are different types of cylinder:
Disposable and non-refillable cylinders 4
Refillable cylinders 4
Recovery cylinders 4
Normally, each cylinder is equipped with a safety-relief device that
will vent pressure from the cylinder before it reaches the rupture
point, in the event of, say, overheating. When temperatures increase,
the liquid refrigerant expands into the vapour space above the liquid
causing the pressure to rise gradually as long as a vapour space is
available for expansion. However, if no vapour space is available due
to an overfilled cylinder and no pressure-relief valve is available, the
liquid will continue to expand with no room for the expanding liquid
and will result in extremely high pressures with the consequence
of the cylinder rupturing. When the cylinder ruptures, the pressure
drop causes the liquid refrigerant to flash into vapour and sustains
explosive behaviour. The rupture of a refrigerant cylinder containing
liquid refrigerant that flashes into vapour is far worse than the rupture
of a compressed-air cylinder of the same pressure. The next pages
include information on cylinder management plans.
61

3
Refrigerant Management
Disposable and non-refillable cylinders
Available on the market are a type of cylinder called “non-refillable”
or “disposable” cylinders. These are sometimes used where the
supply infrastructure is less comprehensive, and it is less costly
for refrigerant suppliers who may expect their cylinders to become
lost. From both an environmental and safety perspective, the use of
disposable cylinders is considered to be very bad practice.
These containers are generally discharged after use, resulting in a lot
of refrigerant being released to the atmosphere. Furthermore, there
are often attempts to re-use these cylinders (for example, through
brazing new valves onto them to enable re-filling with refrigerant),
despite such practices being forbidden. Also, they tend to be
manufactured from thinner metal than the conventional, re-usable
cylinders, rendering them more susceptible to rusting and mechanical
damage over time. As such, their use is not recommended under any
circumstances.
In fact they are already prohibited in many countries, such as the
European Union member states and Australia and Canada. Other
countries are also working to implement similar rules. Mandating the
use of returnable, refillable containers was implemented as a key
measure to reduce GHG emissions by eliminating the possibility of the
eventual release of the residual product that unavoidably remains in
disposable refrigerant containers. These regulations had support from
the major refrigerant manufacturers and industry trade associations.
If a disposable cylinder has been used, before disposing of it, it
should be properly emptied. This requires the remaining refrigerant
to be recovered until the pressure has been reduced to pressure
of approximately 0.3 bar (absolute). The container’s valve must be
closed at this time and the container marked as empty. The container
is then ready for disposal. It is recommended that the cylinder valve
should then be opened to allow air to enter, and the cylinder should
be rendered useless (with the valve still open) by breaking off the
valve or puncturing the container. This will avoid misuse of the
container by untrained individuals. Used cylinders can be recycled
with other scrap metal. Never leave used cylinders with residual
refrigerant outdoors where the cylinder can rust. An abandoned
cylinder will eventually deteriorate and could potentially explode.
Refillable cylinders
Refillable cylinders are the standard receptacles available for the
storage and transportation of smaller quantities of refrigerant. They
normally range in size from about 5 litres to 110 litres (approximately
5 to 100 kg of CFC, HCFC or HFC refrigerant). The cylinders are
normally constructed from steel and have a combination valve,
with separate ports for refrigerant removal, refrigerant filling and
a pressure relief device. The port for refrigerant filling is normally
locked so that only the refrigerant supplier can gain access. Some
cylinders also have two separate removal ports: one for liquid and
another for vapour, if the cylinder is fitted with a dip-tube. There is
usually a metal collar around to the top of the cylinder to protect
the valve from mechanical damage. Both the cylinder itself and the
valve are usually subject to national regulations for their design,
fabrication, and testing.
62

3
Refrigerant Management
Recovery cylinders
CHAPITRE 3
PAGE 6
Recovery cylinders are specifically intended for refrigerant that
have been removed from refrigeration systems. The recovered
refrigerant can then be re-used or sent for reclamation or disposal.
The construction of the cylinders is normally very similar to a
conventional refillable cylinder, except for two differences: one is
that the cylinder valve has the refrigerant filling port enabled, so
that refrigerant can be easily fed into the cylinder, and the second
being the external marking. The cylinder shoulder and upper part
is normally painted yellow, with the remainder of the cylinder body
painted grey colour code is also applied to cylinder to indicate the
type of recovered refrigerant, as shown in the illustration.
Recovery Cylinder
Vapor
Liquid
Recovery Cylinder
Yellow
Cutaway view
Grey
It is important to ensure that the recovery cylinder is only ever
used for one type of refrigerant. This rule should be followed for
two reasons: first, if different refrigerants are mixed, it may not be
possible to separate them again for re-used, and secondly, mixing
two or more refrigerants can result in a pressure that exceeds the
pressure of either of the refrigerants added into the cylinder.
For refrigeration technicians using recycling machines, it is
suggested that the refrigeration technician utilise a ‘CLEAN’
recovery cylinder for recycled refrigerant and a ‘DIRTY’ recovery
tank for recovered, but not recycled refrigerant. Marking the
recovery tanks as clean and dirty will avoid contamination of
otherwise clean refrigerant by putting clean refrigerant into a
recovery tank that once held dirty refrigerant.
63

3
Refrigerant Management
Management:
Cylinder inspections and re-testing
The use of the various refrigerants in cylinders that are exposed to
the environment, is reason for concern, as previously discussed.
Although the interior of these cylinders must be void of moisture, the
exterior cannot avoid it. Thus, corrosion can and does occur, as well
as mechanical damage due to mishandling. These are but a few of
the reasons why the cylinders must be inspected and re-tested at
particular intervals. The intervals differ by country, but the date for
the next inspection or testing is usually indicated on the cylinder. It
should then be returned to the refrigerant supplier. Similarly, the valves
should be periodically examined, especially the relief valve. Check to
be sure that nothing is obstructing the relief valve and that no visual
deterioration or damage has occurred. If any damage is visible, empty
the cylinder and have the tank repaired. Never use a cylinder with a
faulty pressure-relief valve or with obvious structural impairments.
Elements of the refrigerant management strategy should include:
Refrigerant conservation 4
Refrigerant emissions 4
Containment 4
Refrigerant recovery and recycling 4
Identification of refrigerants 4
64

3
Refrigerant Management
Refrigerant conservation
Refrigerant conservation is part of a refrigerant management
strategy. It is an effort to extend the lifetime of used refrigerant by
establishing methods to contain, recover, recycle, and reclaim for
the purpose of reuse and minimising emissions to the environment.
Containment is important not only to protect the environment,
preventing refrigerant emissions, but also to ensure proper
functioning and efficiency of air-conditioning and refrigeration
systems. Cooling systems are designed as sealed units to provide
long term operation with a fixed charge of refrigerant. Conservation
is affected by the design, installation, service and disposal of
the refrigerating system. Guidelines and standards are being
developed and updated in several countries with consideration to
environmental matters and improved conservation.
Refrigerant emissions
Refrigerant emissions to the atmosphere often occur without
identification of the cause. However, the identification of the
sources of refrigerant leaks is necessary to limit emissions.
Refrigerant emissions occur because of the following:
• Tightness degradation due to temperature variations, pressure
cycling, and vibrations that can lead to unexpected leaks
• Component failures from poor construction or faulty assembly
• Losses due to refrigerant handling during maintenance (e.g.
charging the system), and servicing (e.g. opening the system
without previously recovering the refrigerant)
• Accidental losses (e.g. natural disasters, fires, explosions,
sabotage, and theft)
• Losses at equipment disposal that is due to venting, rather than
recovering refrigerant at the end of the system’s life
When designing, installing and servicing refrigeration systems,
technicians should keep these causes in mind, and work on
systems in ways that avoid them occurring.
Containment
Containment is the general concept of retaining the refrigerant
within the equipment by having leak-proof joints and seals,
pipelines, etc, and handling the refrigerant in a manner that
minimises refrigerant releases.
Leak detection is a basic element of containment and must take
place in manufacturing, commissioning, maintenance and servicing
of refrigerating and air-conditioning equipment, as it allows
measuring and improving conservation of refrigerants.
There are three general means of identifying whether refrigerant may be
leaking from a system:
a) Global methods - such as fixed refrigerant detectors, which
indicate that there is the presence of refrigerant, but they
do not actually locate a leak. They are useful at the end of
manufacturing and each time the system is opened up for repair
or retrofit.
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b) Local methods - where a technician uses gas detection
equipment to manually pinpoint the location of the leak. This is
the usual method used during servicing.
c) Automated performance monitoring systems – which indicate
that a leak exists by alerting operators to changes in equipment
performance. This can indicate that there is a deficit of
refrigerant within the system.
It is important to recognise the
difference between “refrigerant
detection” and “leak detection”:
refrigerant detection is the
identification of the presence of
refrigerant, and leak detection is the
identification of the location where
refrigerant is, or could be, emitted
from. Thus, refrigerant detection is
normally required for detecting leaks,
but it requires the technician to
manually search for the leak source.
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Refrigerant recovery and recycling
The need to adopt refrigerant conservation has led the industry to
develop a specific terminology which is used in this section.
According ISO 11650 standard, these definitions are:
• Recovery means to remove refrigerant in any condition from a system
and store it in an external container. Practical aspects of recovery
procedures, and examples of refrigerant recovery operations in
refrigeration equipment and systems how this might be done.
• Recycling means to extract refrigerant from an appliance and
clean it using oil separation and single or multiple passes through
filter-driers which reduce moisture, acidity, and particulate matter.
Recycling normally takes place at the field job site.
Recovery methods 4 Recycling of refrigerant 4
There is also potential to reclaim refrigerants as outlined in:
Refrigerant recovery and recycling equipment 4
Information on testing refrigerants for recycling and reuse can be found in:
Identification and testing of refrigerants 4
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CHAPITRE 3
PAGE 10
Recovery methods
Since a recovery unit will remove more refrigerant from a system than
any other practicable method, its use should be regarded as the norm and
not the exception. Recovery units are being more widely used due to their
increasing availability. It is important to use appropriate equipment
considering the characteristics of the refrigeration or air conditioning
system and the technical specifications of the recovery unit
regarding mainly capacity of the unit, rate of recovery, and type of
refrigerant that can be recovered. As with vacuum pumps, recovery
Condenser
Filters
Oil Separator
Receiver
Compressor
Accumulator
units will work much more efficiently if connection hoses are kept as
short and as large in diameter as possible. However, not being able
to get a recovery unit close to a system is not an acceptable excuse
for not using one. If long hoses have to be used, all that will happen
is that recovery will take longer. There is no longer any acceptable
reason or excuse for releasing refrigerants into the atmosphere.
These images show a typical configuration and the main components of a
recovery unit.
High-Pressure
Cuto�
Coaxial Coil
68
Configuration and
the main components
of a recovery unit

3
Refrigerant Management
Open
Refrigerant recovery unit
Open Open
Open
Recovery Unit
Using recovery units
Recovery units are connected to the system by available service
valves or line tap valves or line piercing pliers as shown in the
image. Some of them can handle refrigerants in vapour phase and
others in both vapour and liquid phases by throttling the liquid
before it enters the compressor. For vapour-only recovery machines,
it must be ensured that the compressor does not suck in liquid
refrigerant as this will cause serious damage. Many have onboard
storage vessels.
Recovery Cylinder
CHAPITRE 3
PAGE 11
Scale
Connection of a recovery unit to a refrigeration system
69

3
Refrigerant Management
CHAPITRE 3
PAGE 11
Vapour recovery mode
Vapour transfer
The refrigerant charge can be recovered in vapour recovery mode
as shown in this diagram.
DISABLED
UNIT
Vapour recovery mode
Vapor Side
Liquid
Vapor
SCALE
Drier
Vapor
Liquid
Recovery
Cylinder
RECOVERY
UNIT
On larger refrigeration systems this will take appreciably longer
than if liquid is transferred. The connection hoses between recovery
units, systems and recovery cylinders should be kept as short as
possible and with as large a diameter as practicable.
Liquid transfer
Until recently, it was unheard of to recover direct liquid. But with the
use of oil-less compressors and constant pressure regulator valves,
it’s become the preferred method of recovery by most recovery
Inlet
Outlet
equipment manufacturers. Oil-less recovery equipment has an
internal device to flash off the refrigerant. Oil-less compressors will
tolerate liquid only if metered through a device like a CPR (crankcase
pressure regulating) valve. Don’t attempt to use the liquid recovery
method unless your unit is designed to recover liquid.
Liquid recovery is performed the same way as standard vapour
recovery. The only difference is that you will connect to the high
side of the system. Recovering liquid is ideal for recovering large
amounts of refrigerant.
If the recovery unit does not have a built-in liquid pump or is
otherwise not designed to handle liquid, then liquid can be removed
from a system using two recovery cylinders and a recovery unit. The
recovery cylinders must have two ports and two valves, one each for
liquid and one each for vapour connections. Connect one cylinder
liquid port directly to the refrigeration system at a point where liquid
refrigerant can be decanted. Connect the same cylinder vapour port
to the recovery unit inlet. Use the recovery unit to draw vapour from
the cylinder, thereby reducing the cylinder pressure, which will cause
liquid to flow from the refrigeration system in to the cylinder. Take
care as this can happen quite quickly.
The second cylinder is used to collect the refrigerant from the
recovery unit as it draws it from the first cylinder. If the recovery unit
has adequate onboard storage capacity this may not be necessary.
Once the entire liquid refrigerant has been recovered from the
refrigeration system, the connections can be relocated and the
remaining refrigerant recovered in vapour recovery mode.
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CHAPITRE 3
PAGE 12
Liquid recovery using a vapour only recovery machine
It may be and found two convenient recovery cylinders to fit a liquid sight glass within the
transfer line. Do not connect the liquid line to the transfer unit
compressor otherwise it will be damaged. The set-up of this scheme is
illustrated here:
refrigeration
system
st
1 recovery cylinder
vapour-only recovery
machine
nd
2 recovery cylinder
Liquid recovery using a vapour only recovery machine and two recovery
cylinders
Push and pull liquid recovery
There is another method for liquid recovery; more common than
that described previously, called the “push and pull” method. If you
have access to a recovery cylinder, the procedure will be successful
CHAPITRE 3
if you connect the recovery cylinder to the recovery units vapour
valve, and the recovery cylinder liquid valve to the liquid side on the
PAGE 13
disabled unit as shown in the diagram. The recovery unit will pull
the liquid refrigerant from the disabled unit when decreasing the
Push and pull recovery method
pressure in the recovery cylinder. Vapour pulled from the recovery
cylinder by the recovery unit will than be pushed back to the
disabled unit’s vapour side.
DISABLED
UNIT
Vapor Side
Liquid Side
Sight
Glass
Push and pull recovery method
SCALE
Drier
Vapor
Liquid
71
Inlet
Recovery
Cylinder
Outlet
RECOVERY
UNIT

3
Refrigerant Management
Using the system’s own compressor
If the refrigerant in a system is to be removed and the system has a
working compressor, it is possible to use the compressor to recover
the refrigerant. It may be possible to pump the system down in the
normal way and then decant the refrigerant into a cooled recovery
cylinder, or it may only be possible to use the cooled recovery
cylinder as both condenser and receiver by installing it at the
compressor outlet, as shown in this diagram.
Capillary tube
Closed
Filter-drier
Compressor
operating
Open
Vapor valve
open
Recovery Cylinder
packed in ice
Using the compressor
to recover the refrigerant
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Recycling of refrigerant
Recovered refrigerant may be reused in the same system from
which it was removed or it may be removed from the site and
processed for use in another system, depending upon the
reason for its removal and its condition, i.e., the level and types
of contaminants it contains. There are many potential hazards in
the recovery of refrigerants, and recovery and reuse need to be
monitored carefully. Potential contaminants in refrigerant are acids,
air, moisture, high boiling residues and other particulate matter.
Even low levels of these contaminants can reduce the working life
of a refrigeration system and it is recommended that recovered
refrigerant should be checked before reuse.
Refrigerant from a unit with a burnt-out hermetic compressor is reusable
providing it has been recovered with a recovery unit incorporating an
oil separator and filters and that it has been checked for acidity. To
check the acid content of any reclaimed oil it is necessary to use
a refrigeration-oil-test-kit. Usually it is only a matter of filling a test
bottle with the oil to be tested and mixing it with the test liquid inside.
If result shows purple: oil is safe. If liquid turns yellow this would
show the oil is acidic - and refrigerant/oil should not be used in
system. Such material should be sent for reclamation or destruction.
Refrigerant recycling
There are in the market several units that recovers, recycles,
evacuates and recharges – all in one fast, continuous operation
through one hook-up; these are called refrigerant recycling
machines. If it is to be returned, the next issue is the condition
of the refrigerant. When the oil is separated from the refrigerant,
the vast majority of the contaminants are contained in it. Most
refrigerant recycling machines utilise filter-driers to remove
any other moisture and acid as well as particles. It is generally
acceptable to return this refrigerant to the system.
CHAPITRE 3
The real problem occurs when there is a burnout in a hermetic
compressor. PAGE A 15burnout
is the result of electrical failure inside the
compressor of the refrigeration system. This can be due to variety
of factors. Typical Contamination single pass of system the refrigerant in this situation can
range from mild to severe. Two recycling standard methods are
used by equipment on the market. The first is referred to as single
pass, and the other is a multiple pass. There is equipment that
provides operation in both methods.
• The single pass recycling machines process refrigerant through
filter-driers and /or distillation. It makes only one trip from the
recycling process through the machine and then into the storage
cylinder. This image shows a typical single pass system.
MANIFOLD
PRE-FILTER
RECOVERY
UNIT
CONDENSER
FILTER
DRIER
SYSTEM
Typical single pass system
AC UNIT
OIL
SEPARATOR
ACCUMULATOR
OIL
DRAIN
PURGE
UNIT
RECOVERY
CYLINDER
FILTER
DRIER
73
COMPRESSOR
OIL
DRAIN
OIL
SEPARATOR
OIL RETURN

3
Refrigerant Management
CHAPITRE 3
PAGE 16
Typical multi-pass system
• The multiple pass method re-circulates the recovered refrigerant
many times through filter-driers. After a certain period of time
or number of cycles, the refrigerant is transferred into a storage
cylinder. Multiple-passes method recycling takes longer,
but depending on the refrigerant level of contamination and
moisture it may be essential, for example, if it is particularly dirty.
This is shown in the diagram:
MANIFOLD
PRE-FILTER
RECOVERY
UNIT
FILTER
DRIER
SYSTEM
RECEIVER
&
PURGE UNIT
MOISTURE
INDICATOR
Typical multi-pass system
LIQUID
PUMP
AC UNIT
OIL
SEPARATOR
ACCUMULATOR
OIL
DRAIN
CONDENSER
RECOVERY
CYLINDER
RECYCLE
SOLENOID
FILTER
DRIER
COMPRESSOR
OIL
DRAIN
OIL
SEPARATOR
RECYCLE LOOP
OIL RETURN
Refrigerant recovery and recycling equipment
The purpose of refrigerant recovery and recovery/recycling
equipment is to help prevent emissions of refrigerant by providing
a means of temporarily storing refrigerants that have been removed
from systems undergoing service or disposal. Such equipment is
used to temporarily store recovered refrigerant until the system
undergoing repair is ready to be recharged or is prepared for
disposal. Refrigerant recovery equipment may have the ability to
store (recovery only) or the added capability of recycling (recovery
and recycling) refrigerants. The temporary storage capability of the
equipment prevents the release of refrigerants into the atmosphere
that may otherwise exist if the refrigeration and air-conditioning
equipment were opened to the atmosphere for servicing.
The use of refrigerant recovery and recycling equipment is an
essential means of conserving refrigerant during servicing,
maintenance, repair, or disposal of refrigeration and air-conditioning
equipment. Refrigerant recovery and recycling equipment could
be made available to service technicians in every sector. Note that
due to incompatibility issues and the array of refrigerants used
in different sectors, refrigerant recovery/recycling equipment
intended for use with one type of air conditioning system, such as
motor vehicle air conditioners, may not be adequate to service airconditioning
and refrigeration equipment in the domestic, unitary,
or commercial refrigeration and air-conditioning sectors. The types
of refrigerants used in these sectors vary and all recovery/recycling
equipment is not capable of meeting the same requirements.
This is very important to users to ensure that their recovery
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equipment is capable of handling the specific refrigerants that are
used in the system. The specific identification of the equipment is
important throughout its service, disposal or end-of-life.
Recycling equipment is expected to remove oil, acid, particulate,
chloride, moisture, and non-condensable (air) contaminants from
used refrigerants. The effectiveness of the recycling process can
be measured on contaminated refrigerant samples according to
standardized test methods, such as those within the standards
ISO 12810 and ARI 700. Unlike reclaiming, recycling does not
involve analysis of every batch of used refrigerant and, therefore,
it does not quantify contaminants nor identify mixed refrigerants.
Subsequent restrictions have been placed on the use of recycled
refrigerant, because its quality is not proven by analysis.
A variety of recycling equipment is available over a wide price
range. Currently, the automotive air-conditioning industry is the
only application that prefers the practice of recycling and reuse
without reclamation. Acceptance in other sectors depends on
national regulations, the recommendation of the cooling system
manufacturers, the existence of another solution such as a reclaim
station, variety and type of systems, and the preference of the
service contractor. Recycling with limited analysis capability
may be the preference of certain developing countries where
access to qualified laboratories is limited and shipping costs are
prohibitive. For most refrigerants there is a lack of inexpensive
field instruments available to measure the contaminant levels of
reclaimed refrigerant after processing.
Refrigerant recovery equipment has been developed and
is available with a wide range of features and prices. Some
equipment with protected potential sources of ignition also exists
for recovery of flammable refrigerant. Testing standards have been
developed to measure equipment performance for automotive
(SAE) and non-automotive applications (ISO). Although liquid
recovery is the most efficient, vapour recovery methods may be
used alone to remove the entire refrigerant charge as long as the
time is not excessive.
Excessive recovery times should be avoided, since extended
recovery time periods may limit the practical usage of recovery
equipment on the majority of refrigeration or air-conditioning
equipment that contain up to 5 kg of refrigerant. In order to reach
the vacuum levels that are required in some countries for larger
systems, vapour recovery will be used after liquid recovery.
Performance standards for refrigerant recovery equipment are
available for service of both motor vehicle air conditioners (e.g.,
SAE J1990), and stationary refrigeration and air-conditioning
systems (e.g. ARI Standard 740). Adoption of such standards
as a part of common service procedures could be adopted by
regulating authorities.
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Identification and testing of refrigerants
Is very important to know which refrigerant is in a system in order that
correct refrigerant can be used when work is carried out on the system.
Refrigerants may be identified by the following methods:
• Refrigerants stamped on unit data plate, thermostatic expansion
valve, or compressor
• Standing pressure
• Refrigerant Identifier – a portable electronic device that allow the
reliable identification or detection of percentage composition
(not all) of CFCs, HCFCs, HFCs, hydrocarbons (HC) and air
content.
In the case of hermetic systems that have not be opened (i.e., no
sign of post-manufacture manipulation of the system, such as
recent brazing or piercing valves), the first method is adequate. In
other systems, the last method should ideally be used, since it is
the most reliable. If a system has previously been broken into, it is
possible that a retrofitted refrigerant may have been charged into
the system. In this case, the marking on the name plates may not
reflect this, and the standing pressure may be the same for the
original and the new refrigerant.
Testing considerations include:
Test refrigerant for contamination 4
Test oil contamination 4
Checking of refrigerant cylinders 4
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3
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CHAPITRE 3
PAGE 19
Test refrigerant for contamination
Refrigerants can be tested for water/oil contamination and acidity
with a test kit. With the change to alternative refrigerants, in many
cases, has come need for new lubricants. Where retrofit procedures
call for the removal of mineral-based oil and replacement with ester
lubricants, it is necessary to reduce the mineral lubricant to a minimal
level. These test kits provide simple methods of determining the level
of residual mineral oil in an ester lubricant mixture.
Test oil contamination
It is possible to test the oil in some systems for acidity. Acid in the
oil indicates that burnout or partial burnout has taken place, and/or
that there is moisture in the system, which can cause a burnout.
To carry out an oil test it is necessary to remove a sample of oil from
the compressor without undue release of refrigerant. The procedure
for this will vary depending
TEST KIT
on the arrangement of shutoff
valves and access to the oil
available on the unit. For many
hermetic compressors there
will be neither shut off valves
nor access. This image shows
an example of a refrigerant
testing kit.
Refrigerant testing kit
The refrigeration oil acid test kit is one-bottle (one step) test, and
is the fastest way of determining if compressor oil is safe or acidic.
If the test result in the mixture remaining purple, the oil is safe,
whereas if it turns yellow, it is acidic. The ultra-sensitive colour
change guarantees an accurate test.
Checking of refrigerant cylinders
Decanting refrigerants into service cylinders is a hazardous practice.
It should always be carried out using the method prescribed by the
refrigerant manufacturer.
Special care should be taken:
• Not to overfill the cylinder
• Not to mix grades of refrigerant or put one grade in a cylinder
labelled for another CHAPITRE 3
• To use only clean cylinders, PAGE free 20 from contamination by oil, acid,
moisture etc.
Cylinder with separate liquid and gas valves
• To visually check each cylinder before use and make sure all
cylinders are regularly pressure tested
• Recovery cylinders should have a specific indication depending
on the country in order not to be confused with virgin refrigerant
container
• Cylinders should have
separate liquid and gas
valves and be fitted with a
pressure relief device, as
shown in the diagram:
Cylinder with separate liquid and
gas valves
Vapor
Liquid
77
Yellow
Cutaway view
Grey

3
Refrigerant Management
Recognising Refrigerant cylinder colour codes
Refrigerant cylinders or drums are often colour coded. The colour code is normally a voluntary precaution followed by refrigerant
suppliers. However, it should be noted that different colour codes are used in various parts of the world.
Refrigerant cylinder colour codes according to ARI (2008)
Colour
PMS
number Refrigerants
White N/A R12
Orange 21 R11, R404A
Yellow 109 R500
Yellow-Brown (Mustard) 124 R14, R401B
Yellow-Orange 128 R422A
Cream 156 R407B
Pinkish-Red (Coral) 177 R14, R401A
Red 185 HCs
Maroon 194 R245fa
Medium Purple (Purple) 248 R406A
Light Purple (Lavender) 251 R403B, R502
Dark Purple (Violet) 266 R113, R411A
Warm Red 292 R423A
Dark Blue (Navy) 302 R114, R506B
Blue-Green (Teal) 326 R411B, R507A
Deep Green 335 R124
Light Green 352 R22
Green 354 R417A
Colour
PMS
number Refrigerants
Lime Green 368 R407A
Green-Yellow 375 R422D
Yellow-Green (Lime) 381 R416A
Green-Brown (Olive) 385 R402B
Dark Grey (Battleship) 424 R116, R236fa
Light Blue-Grey 428 R23, R123
Light Brown (Sand) 461 R402A
Medium Brown (Tan) 465 R125, R409A
Dark Brown (Chocolate) 450 R407D
Medium Brown (Brown) 471 R407C
Rose 507 R410A,
Light Blue (Sky) 2975 R13, R134a
Medium Blue (Blue) 2995 R414B
Deep Blue 3015 R413A
Blue-Green (Aqua) 3268 R401C, R503
Green-Blue (Jungle Green) 3405 R427A
Beige 4545 R414A
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PAGE 22
Examples of colour-coded refrigerant cylinders
Examples of colour-coded refrigerant cylinders
R-22 R-123 R-124 R-125 R-134A R-23 R-401A
R-401B R-402A R-402B R-403B R-404A R-407C R-408A
R-409A R-401A R-413A R-417A R-507 R-508B
Decant Recovery Care 10 Care 30 Care 40 Care 45 Care 50
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Examples of refrigerant recovery
Now you have relevant download and read the briefing, attempt to
apply the information to the following examples.
Domestic refrigerator 4
Commercial cold room system 4
Air-conditioning system 4
Mobile air conditioning (MAC) system 4
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3
Refrigerant Management
CHAPITRE 3
PAGE 24
Recovery from a domestic refrigerator
It is possible to recover refrigerant from a hermetically sealed
system, which has no service valve. A line-tap valve (piercing
valve) should be fitted to the system, and a recovery unit used to
remove the refrigerant from the unit via the line-tap as with the
larger system. Line-tap valves should never be left permanently in
place, but removed after use if placed on the process tube (if the
equipment is going for disposal). Because of the small charge of
refrigerant, only vapour recovery is needed.
It is recommended to install tap-valves on both and low pressure side, as
shown here:
Recovery from a domestic refrigerator
Recovery from commercial cold room system
Liquid transfer
Connect the recovery cylinder’s hose to the system’s outlet stop
valve on the condenser/receiver. To control liquid flow, install a
sight glass to the hose and cylinder. From the recovery cylinder’s
vapour side, use a drier. Outlet/discharge side of the recovery unit
goes to the system’s high-pressure side at the inlet condenser
or compressor high-pressure stop valve. All of the system’s stop
valves have to be opened, including the solenoid valves.
Run the recovery unit and keep an eye on the sight glass. When
there is no more liquid transferred through the sight glass, and there
is no icing left on the compressor shell, on the receiver or anywhere
else, this indicates there is negligible amounts of refrigerant left in
the system.
Vapour transfer
When liquid transfer is completed, connect the hoses from the
recovery unit suction/inlet side to the compressor low or highpressure
side. For better recovery, connect hoses to both the high
and low pressure sides using a service manifold. The recovery
discharge/outlet side should be connected to the recovery
cylinder’s vapour side. Be sure that all service/shut off valves are
open to avoid “locking” refrigerant into the system.
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Recovery from air-conditioning system
Liquid transfer
Air-conditioning installations may have service stop valves installed
in the pipe lines. When recovering refrigerant from such a system,
liquid should be transferred first because the quantity can be rather
large. The push-pull method is recommended.
The system’s liquid pipe should be connected to the recovery
cylinder’s liquid side. The cylinder’s vapour side should be
connected to the recovery inlet (suction) side. The discharge side
recovery unit should be connected to the suction pipe on the air
conditioning system. If there are available valves on the systems
receiver (on the high pressure side), the recovery unit discharge side
could be connected here as well. Liquid flows now from the liquid
side of the air-conditioning system and into in the cylinder. The
recovery unit will keep the pressure inside the cylinder lower than in
the air-conditioning system and keep up the liquid flow.
Vapour transfer
When liquid transfer is completed there will still be some refrigerant
vapour left in the system. To transfer all refrigerant to the recovery
cylinder, connect the suction hose from the recovery unit to the
gas pipe on the air-conditioning system. Connect the recovery unit
discharge outlet hose to the recovery cylinder’s vapour side. Run
the recovery unit until the suction gauge reads –0.7 bar (0.3 bar
absolute) or lower.
Recovery from mobile air conditioning (MAC) system
Vapour transfer
MAC systems are normally equipped with service valves on the
compressor’s high and low-pressure sides. The refrigerant charge
on such system is rather small and therefore only vapour transfer
is required. Connect the hose from the recovery unit’s suction/
inlet side to the air-conditioning system’s compressor low-pressure
side and the discharge hose to the vapour valve on the recovery
cylinders. Run the recovery unit for 3 – 5 minutes. Connect another
hose to the system’s high-pressure side and complete the recovery.
Run the recovery unit until pressure gauges reads –0.7 bar (0.3 bar
absolute) or lower.
Refrigerant reclaiming
Reclamation means to reprocess used refrigerant, typically
by distillation, to conditions similar to that of virgin product
specifications. Reclamation removes contaminants such as
water, chloride, acidity, high boiling residue, particulates/solids,
non-condensable, and impurities including other refrigerants.
Chemical analysis of the refrigerant shall be required to determine
that appropriate specifications are met. The identification of
contaminants and required chemical analysis shall be specified by
reference to national or international standards for new product
specifications. Reclamation typically occurs at a reprocessing or
manufacturing facility. Commercial units are available for use with
R12, R22, R134a, etc, and are designed for the continuous use
required on a long run recovery recycling procedure.
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Further reading
UNEP DTIE OzonAction - Guidebook for Implementation of Codes of Good Practice
Refrigeration Sector, 1998
4 www.unep.fr/ozonaction/information/mmcfiles/2174-e.pdf
UNEP DTIE OzonAction - Training Manual on Good Practices in Refrigeration –
Training Manual, 1994
UNEP DTIE OzonAction - Training Manual on Chillers and Refrigerant Management,
UNEP 1994
Ozone Unit of The Former Yugoslav Republic of Macedonia - Manual for Refrigeration
Service Technicians, 2006
4 www.ozoneunit.gov.mk/eng/doc/Training_manual_for_service_technicians.pdf
Stockholm Environment Institute - Interlinked ODS Phase-Out Activities, 2005
4 www.sei.se/publications.html?task=view&catid=1&id=562
Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Proklima – Training
Manual on Good Practices in Refrigeration, GTZ Proklima, 2009
4 www.gtz.de/proklima
83

4
Servicing Content
Practices Avoiding contaminants 4
Servicing RAC systems 4
Detection methods 4
Why charge refrigerant blends as liquids? 4
Further reading 4

Summary
This section will provide the technician with the
ability to understand the causes of main operational
problems presented by vapour compression
refrigeration or air conditioning systems. It is
important to understand how to avoid them through
the adoption of good practices, and to be aware of
the main precautions which should be taken when
servicing installations and systems.
Methods and techniques that are used when working
on systems, primarily during servicing exercises,
are discussed. In particular, this includes the
consideration of system cleanliness (moisture, acid,
non-condensable), and the means for overcoming
these problems, such as proper evacuation methods
and system purging. To avoid such issues in the first
place demands appropriate procedures associated
with tightness testing (“leak testing”) and refrigerant
charging, which are described.
4
Servicing Practices
Technicians have the important role of making the operation of
RAC systems the most energy efficient and decreasing refrigerant
emissions. This can only be achieved by the adoption of good
practices. The section starts with the evaluation of the problems
due to the presence of moisture and contaminants in the system,
and how to avoid them through purging and evacuation, charging,
and leak testing. The important measurement instruments and
tools necessary to achieve good servicing practices are included.
A technician should be should be able to achieve the following
servicing operations:
• Leak detection, purging and evacuation.
• Charging refrigerants.
• Identifying the servicing-specific tubing tools and techniques
of sizing, un-rolling, cutting, bending, flaring, swaging,
piercing, pinching and welding.
• Identifying the proper use of servicing instruments: manifold
gauges, charging scales, and thermometers.

4
Servicing Practices
Avoiding contaminants
Before charging any system with refrigerant, precautions should
be taken to avoid the presence of any type of contaminants in the
system, so classifying contamination types in a refrigeration system
is necessary to identify the proper servicing action required before
charging any system with new refrigerant.
First, the identification of potential contaminants is outlined:
Moisture 4
Non-condensables 4
86

4
Servicing Practices
Moisture
Moisture causes several operating problems in RAC systems and
understanding the basis of these problems is important. Basically,
moisture can be classified as visible and invisible. “Visible” moisture
is high concentration of water and can be seen with the eye, and is
in liquid form. Occasionally, liquid water is found in systems but this
is rather unusual. “Invisible” moisture is water in low concentrations
and cannot be seen with the eye, since it is essentially dissolved in
the refrigerant. It is important to remember that moisture can easily
get into a system but it is difficult to get out.
The main situations and activities that can result in moisture entering the
system are:
• when there is a leak in part of the system that experiences subatmospheric
pressure (thus, drawing air into the system)
• during servicing and repair when the system is opened and
exposed to the air and evacuation is not carried out properly
• when filters or lubricant are exchanged
• during charging with refrigerant and transfer hoses have not
been purged properly.
The technician should be particularly aware of the possible introduction of
moisture when carrying out these activities.
There will always be some moisture within any refrigerating system,
and complete elimination is almost impossible. However, at very
low concentrations the moisture is unlikely to cause any significant
problem. On the other hand, if the moisture is present in higher
concentrations, then a series of problems can arise. The “tolerable”
concentration of moisture differs between refrigerants, oil types,
operating temperatures and compressor designs. Nevertheless, in
almost all systems – except for ammonia systems – the maximum
concentration of moisture should not exceed around 10 ppm.
Above these concentrations, the moisture can have negative effects
on the system, such as reactions with the oil, causing the unit to
malfunction and accelerating burn-out of hermetic compressors.
Recognising the presence of moisture
The presence of moisture within the system can be recognised by certain
observations:
• The system will stop due to low suction pressure, and proceed
to warm up. Since it is the formation of solid ice within the
expansion device that has caused the blockage, the warming
will result in the disappearance of the ice and thus the unit will
work properly again. However, the process will occur again as
the ice once again forms at the expansion device.
• Decreasing pressure, where the suction pressure steadily decreases
over several hours – even to a vacuum. Then pressure suddenly
becomes normal again. This abnormal cycle will keep repeating.
• If, during system shutdown, one warms the refrigerant control
with a safe resistance heater (hot pad) or radiant heat bulb, the
ice will melt. Should the system then begin to work properly,
there is definitely moisture in the refrigerant.
These symptoms are explained by the following:
• The solubility of water in refrigerant reduces with temperature,
so as the refrigerant passes through the expansion device, the
dissolved moisture may become saturated water.
87

4
Servicing Practices
• If the temperature reaches below 0°C, the saturated moisture
(water) within the expansion device can freeze and subsequently
stop the refrigerant flow.
• As the expansion valve warms, due to the lack of refrigerant, the
ice melts and moisture returns to the expansion valve and once
more generates an intermittent cooling.
• Whether or not freezing actually occurs depends primarily upon
the amount of moisture (water) and size of the ice particles
formed.
Be aware of the risk of corrosion and its impacts
In addition to possible freezing, another serious problem – namely
corrosion – can occur within the system due to the presence of
moisture. Corrosion can create serious problems because often
its effects are not apparent until serious damage has occurred.
For example, moisture in the form of water alone can cause rust
after a period of time. However, moisture plus the refrigerant create
much more corrosion problems. Refrigerant such as R12 containing
chlorine will slowly hydrolyse with water and form hydrochloric
acids. This acid greatly increases the corrosion of metals.
The corrosion processes can be characterised as follows:
• Heat increases the rate of corrosion due to acids because at
higher temperatures the acid-forming process is accelerated.
This acid, of course, attacks all the materials it contacts, the rate
of corrosion of the individual materials being determined by their
corrosion-resistant qualities. Steel will generally corrode at lower
moisture levels than copper or brass.
• Compressor lubricant presents another problem caused by
moisture, particularly in the case of polyol ester (POE) and poly
alkyl glycol (PAG) lubricants, used with hydrofluorocarbon (HFC)
refrigerants. In fact, these types of lubricant have an affinity for
moisture and will absorb it rapidly if left open to the atmosphere.
Mineral lubricants do not mix with water in the same range as
polyol ester lubricants.
• Water changed into acid emulsifies with lubricants, the two
forming an intimate mixture of exceedingly fine globules. This
effect is called “sludging” of the oil and greatly reduces its
lubricating ability. Corrosion becomes troublesome from the
operating standpoint when the metallic surface is eaten away
and a solid, detachable product is formed. This formation is
commonly known as “sludge”. Sludge exists as slimy liquids, fine
powders, granular solids or sticky solids and causes a variety
of problems. They can plug fine strainers, expansion valves and
capillary tubes. And because they usually contain acids they
corrode whatever they cling to, accelerating damage.
Eliminating moisture problems
To eliminate moisture problems it is necessary to take precautions
and actions, which will ensure a moisture-free system. It is important
to change the filter drier frequently. The most effective way to
eliminate moisture from a system is through the use of a high vacuum
pump to create a vacuum deep enough to evaporate and remove
this moisture. The recommended level of evacuation is of 1 millibar
absolute (100 Pa) to achieve the evacuation of moisture. This level
of vacuum must be maintained for 10 minutes without the help of a
vacuum pump.
88

4
Servicing Practices
Non-condensables
Gases in the system which do not liquefy in the condenser are
contaminants and reduce the cooling capacity and system
efficiency. The quantity of non-condensable gas that is harmful
depends on the design and size of the refrigeration system and
nature of the refrigerant. Their presence contributes to higher
than normal discharge pressures and resultant higher discharge
temperature. Higher temperatures speed up undesirable chemical
reactions. Gases found in hermetic refrigeration units include
nitrogen, oxygen, carbon dioxide (CO2, R744), carbon monoxide,
methane and hydrogen.
These non-condensable gases infiltrate sealed systems in the following
manner:
• They are present during equipment manufacture or servicing
and remain due to incomplete evacuation.
• They are desorbed from various system materials or are formed
by decomposition of gases at elevated temperatures during
system operation.
• They enter through low side (below atmospheric pressure)
leakage points.
• They are formed from chemical reactions between refrigerants,
lubricants and other materials during operation. Chemically
reactive gases, such as hydrogen chloride, attack other
components in the refrigerating system; in extreme cases, the
refrigerating unit fails.
• They are introduced when connecting refrigerant hoses that
have not been properly purged.
Whilst designing, installing and servicing systems, technicians
should be aware of these routes to contamination, and adjust their
behaviour accordingly.
89

4
Servicing Practices
Servicing RAC systems
The main concept and procedures of each operation is the same
for all refrigeration and air-conditioning systems. They differ only in
each system specific connectivity requirements or tools to be used.
Most of servicing activities to RAC systems –dealing with refrigerants – falls
within the one of the following main operations:
Evacuation 4
Purging (cleaning) 4
Leak detection 4
Charging 4
Recovery 4
90

4
Servicing Practices
Evacuation
A refrigerating system must contain only the refrigerant in liquid or
vapour state along with dry oil. All other vapours, gases, and fluids
must be removed. Connecting the system to a vacuum pump and
allowing the pump to run continuously for some time while a deep
vacuum is drawn on the system can best remove these substances.
It is sometimes necessary to warm the parts to around +50°C
while under a high vacuum; in order to accelerate the removal of all
unwanted moisture, heat the parts using warm air, heat lamps, or
water. Never use a brazing torch. If any part of the system is below
0°C, the moisture may freeze and it will take a considerably longer
time for the ice to sublimate to vapour during the evacuation process.
The equipment necessary to carry out the evacuation is:
PAGE 06
PROCEDURES TO PERFORMS
• vacuum pump
• manifold gauges
two servicing valves (in the case system is not equipped with
servicing valves)
• vacuum gauge.
It is essential to know that conventional manifold gauges have
low sensitivity, particularly at lower pressures. As such, they are
ineffective at determining whether or not a sufficient vacuum has
been achieved. Therefore it is essential to ensure that a proper
vacuum gauge (such as a Pirani gauge) is used.
To understand why system evacuation is very important for moisture
elimination, it is useful to remember the concept of vacuum and the
relationship between boiling temperature and pressure. For a pure
substance, like water, the boiling temperature for a fixed pressure
is called saturation temperature at this pressure, and the pressure
at which the water evaporates at a fixed temperature is called
saturation pressure at this temperature.
The relationship between these two thermodynamic properties (a natural
law) is presented in the figure for water:
PRESSURE [kPa]
160
140
120
100
80
60
40
20
0
-75 -35 5 45 85 125
TEMPERATURE [ ° C]
Saturation pressure
and temperature curve
for water
It can be seen in this figure that as the pressure reduces, the
boiling temperature will be lower. If one wants to remove moisture
in DONE
vapour phase from a refrigeration system, it is very important to
lower the system pressure because this will facilitate the change of
the moisture from liquid to vapour phase (through heat transfer from
the surrounding environment) making its removal easier.
Always evacuate a system when:
• replacing a circuit component (compressor, condenser, filterdrier,
evaporator, etc.)
• whilst the system has no refrigerant
• if the refrigerant is contaminated
• after the lubricant is charged.
91

4CHAPITRE 4
PAGE 06
EVACUATION
Servicing Practices
Procedures to perform evacuation
To evacuate and dehydrate a system, before filling with refrigerant, take the
following steps:
1 - First, the system should be tightness tested (i.e., “leak tested”). This
can be done by pressurising the system with oxygen free, dry nitrogen
(OFDN). Shut off the supply of nitrogen and check the pressure over a
period of time (a minimum of 15 minutes, but it depends upon the size
of the system; a larger system requires more time). Keep checking the
pressure gauge to see if the pressure reduces.
2 - If the pressure does fall, it is likely that the system has a leak, so
leak searching and repair procedures must be carried out.
OPEN
OPEN
Vacuum pump connexion
OPEN
Exhaust
3 - When the system is confirmed to be leak-tight, release the OFDN and
immediately connect a proper vacuum pump to both suction side
and discharge the side of the compressor (see diagrams), and make
sure the vacuum gauge is connected. Open all the valves, including
solenoid valves, so there is no part of the circuit that is “locked” in.
4 - Switch on the vacuum pump and wait.
5 - When satisfactory vacuum has been reached (below 100 Pa abs.)
stop the pump and leave it for an appropriate length of time (around
half an hour for a small hermetic system, to several hours for a
large site-installed system) to see if the vacuum gauge indicates an
increase in internal pressure. If the pressure rises there could be two
reasons for it: either there is a leak or moisture still in the system.
In this case, the evacuation
procedure should continue,
but if a constant vacuum
pressure is never achieved,
then it is likely that a leak is
present and the tightness
test should be repeated.
Vacuum Pump
6 - If the vacuum pressure
remains constant over a
period of time, the circuit is
correctly evacuated; dry and
free of leakage.
92

4
Servicing Practices
7 - For large systems where is expected excess of moisture content,
apply indirect heat (using a heat lamp or hot air-blower, see the
diagram) to the system tubing (applying heat to one side only will
cause moisture condensation in the coolest part).
REFRIGERANT
DRUM
VACUUM
PUMP
Refrigeration system evacuation
CENTER GAGE HOSE
USED FOR BOTH
PUMP AND
SUPPLY CYLINDER
HEAT
MOISTURE
ALL SERVICE VALVES ARE
MIDSEATED AND LEAKPROOF
PROTECTIVE CAPS ARE ON TIGHT
MOISTURE
HEAT
U TUBE MERCURY
MANOMETER
LIQUID WATER VAPOR
MOISTURE
HEAT LAMP
93

4
Servicing Practices
Moisture removal
EXHAUST
OPEN
OPEN
OPEN
VACUUM PUMP
8 - In case of closed solenoid valves in the system,
air is usually trapped in-between valves where
they should be opened manually if supplied
with open screws, by applying direct electrical
source to solenoid coil, or by using a service
hand magnet.
9 - Charging of refrigerant can now begin, either
direct to the high-pressure liquid side or
charging into the suction side when the
compressor is running.
94

4
Servicing Practices
Pressure units for vacuum
A variety of different units of measurement
are employed for quantifying pressures,
which can easily lead to confusion. The
below Table 4.1 provides a conversion
of certain units of pressure for standard
atmospheric pressure, 1 bar, and the
recommended highest level of vacuum
(ideally, evacuation pressure should be
below this). Note also that the pressures are
indicated in absolute pressure, not gauge
pressure.
SI units
Standard
atmosphere
1 bar (absolute)
Preferred vacuum
level (absolute)
bar 1.01325 bar 1 bar 0.001 bar
kilo Pascal 101.3 kPa 100 kPa 0.10 kPa
micron 1013250 microns 1,000,000 microns 1000 microns
millibar 1013.25 mbar 1000 mbar 1 mbar
Pascal (Pa)
Non-SI units:
101325 Pa 100,000 Pa 100 Pa
inch of mercury 30.5 in Hg 29.5 in Hg 0.030 in Hg
mm of mercury 760 mm Hg 750 mm Hg 0.75 mm Hg
Torr 760 Torr 750 Torr 0.75 Torr
pounds (force)
per square inch
15.0 psi 14.5 psi 0.015 psi
95

4
Servicing Practices
Purging
The process of removing unwanted gases, dirt or moisture from the
system is called purging. An inert gas such as nitrogen is introduced
in the system to flow through the tubing, forcing unwanted
contaminants out.
Flow pressure
adjustment
Flow
pressure
1/4’’ male �are �tting
for hose connection
Cylinder
pressure
Cylinder
connection
The following equipment is needed to perform purging:
• Oxygen free dry nitrogen cylinder equipped with pressure
regulator
• Nitrogen cylinder equipped with pressure regulator
• Manifold gauges with hoses
• Vacuum pump
• Two servicing valves (or the system is equipped with servicing
valves).
NITROGEN
2350 psig
96

CHAPITRE 4
4PAGE 10
LEAK DETECTION
Servicing Practices
Purging procedure
The following steps should be followed when performing system cleaning
(purging):
1 - Set the connections as shown here:
NITROGEN
PRESSURE
REGULATOR
NITROGEN
CYLINDER
NITROGEN
ESCAPING
NITROGEN
ESCAPING
2 - As with the evacuation procedure, ensure that all stop valves,
solenoid valves and other such devices have been fully opened so
not to restrict the flow around any parts of the system.
3 - Open the low-pressure side and high-pressure side valves in the
manifold gauges.
4 - Open the nitrogen cylinder main valve using the pressure regulator
on the cylinder to keep pressure of OFDN at less than the maximum
working pressure indicated on the equipment nameplate.
5 - Keep the OFDN flowing for several
minutes or until dry clean gas is
discharged, indicating that all the
contaminants have been removed.
6 - Remove the residual nitrogen with
a vacuum pump using the proper
procedure.
97

4
Servicing Practices
Leak detection
RAC systems are designed to operate adequately with a fixed
charge of refrigerant. If it has been determined that a system has
insufficient refrigerant, the system must be checked for leaks, then
repaired and recharged.
Refrigerant leaks are caused by material failure. The mechanism that
creates the material failure is normally attributable to one or more of the
following factors:
• Vibration – Vibration is a significant factor in material failure and
is responsible for “work hardening” of copper, misalignment of
seals, loosening of securing bolts to flanges, etc.
• Pressure changes – Refrigeration systems depend on the changes
in pressure for their operation. The rate of change of pressure
has different effects on the various components in the system,
which results in material stress and differential expansion and
contraction.
• Temperature changes – Refrigeration systems frequently consist
of different materials of differing thickness. Rapid changes in
temperature result in material stress and differential expansion
and contraction.
• Frictional wear – There are many cases of frictional wear causing
material failure, and they vary from poorly-fixed pipework to
shaft seals.
• Incorrect material selection – In a number of cases, inappropriate
materials are selected e.g., certain types of flexible hoses have
a known leakage rate, and materials that are known to fail under
conditions of vibration and transient pressure and temperature
changes are used.
• Poor quality control – Unless the materials used in the refrigeration
system are of a high and consistent standard, changes in
vibration, pressure and temperature will cause failure.
• Poor connections – Poorly made connections, either brazed joints,
screwed connections, or not replacing caps on valves, can allow
refrigerant to escape.
• Corrosion – Exposure to a variety of chemicals or the weathering
can result in a variety of different corrosion modes, which decays
the construction material resulting in the eventual creation of holes.
• Accidental damage – Accidental mechanical impacts to
refrigerant-containing parts can happen under many
circumstances, and therefore it is appropriate to ensure that all
parts of the system are protected against external impacts.
Designers, installers and service
and maintenance technicians should
all be aware of these phenomena,
and always check to see if any are
occurring or leading to leakage
whenever possible.
98

4
Servicing Practices
Detection methods
When a system is thought to have a leak, the whole system should be
checked, with leaks found being marked for rectification. One should never
assume a system has only one leak.
Leak detection is the manual procedure, carried out by a qualified
technician, of checking refrigeration systems to identify possible
leaks in tubes, joints and/or connections, etc.
Generally, the main methods for detecting leaks in the servicing field are:
Using soap solution 4
Using an electronic refrigerant detector 4
Using an ultra-violet lamp 4
Using a halide torch 4
Note: Fault-finding
There are a number of problems that may develop in RAC systems
that would have the same symptoms as a refrigerant leak. For
example: the fan, the compressor and various controls could be
in operation, but the system is not cooling. It is sensible to always
determine the other possible reasons for poor operation before
recharging the refrigerant into a system. Also adding refrigerant to
a system that does not necessarily need it can adversely affect its
performance, including reducing its efficiency. It can also present
significant safety hazards such as causing elevated pressures
above what the system can tolerate.
Topping-up
If a system has a deficit of refrigerant, it is highly likely that this is
because of a refrigerant leak. Often, technicians take the approach
of quickly “topping-up” a system to its original charge amount,
since this a quick and easy way of getting the system to work
properly again. However, this is only a temporary, costly, and
environmentally unacceptable approach to take.
No refrigerant should be added to the system without first
locating and repairing the leaks. Simply adding refrigerant will
not permanently correct the problem, and in fact, it accelerates
the degradation of the system in the longer term, thus reducing
its operational lifetime. Instead, the technician should identify the
leaks before recovering the refrigerant, to avoid contaminating
the surrounding air with refrigerant from a newly open system,
remembering that refrigerant should not be vented to the air.
99

CHAPITRE 4
PAGE 12
4TOPPING-UP
Servicing Practices
APITRE 4
E 12
AP-SOLUTION
Using soap-solution
A water-soap solution is the most popular, minimal cost, and one of
the most effective methods used among servicing technicians.
Applying a soap solution to joints, connections and fittings while system
is running or under a standing pressure of nitrogen helps to identify leak
points when bubbles appear, as shown here:
Use of soap-solution for leak detection
Using an electronic refrigerant detector
Electronic refrigerant detectors contain an element sensitive to a
particular chemical component in a refrigerant. The device may be
battery or AC-powered and often has a pump to suck in the gas
and air mixture. Often, an audible “ticking” signal, and/or visible
flashing indicating lamp increases in frequency and intensity as
the sensor analyses higher concentrations of refrigerant, which
suggests to the operator that the source of the leak is closer.
LEAK DETECTOR
Many refrigerant detection devices also have varying sensitivity ranges that
can be adjusted, as shown here:
SENSING
BULB
ON / OFF
SWITCH
Electronic refrigerant detector
ON
BAT.
OFF
FLEXIBLE
PROBE
Many modern refrigerant detectors have selector switches for
switching between refrigerant types, e.g. chlorofluorocarbons
(CFCs), hydrochlorofluorocarbons (HCFCs), HFCs or HCs. HCFCs
have less chlorine than CFCs and the sensitivity has to be changed
by the selector switch. When using electronic refrigerant detectors
in a workshop, always ensure good ventilation since sometimes
it gives false signals due to other refrigerants being present in the
surrounding area.
Electronic refrigerant detectors may be used to detect hydrocarbons
(HCs), but the sensitivity may not be adequate, or may need recalibration.
The detection equipment should be calibrated in a
refrigerant-free area. Ensure that the detector is not a potential source
of ignition and is suitable for hydrocarbon refrigerants.
100
BATTERY
LIFE
INDICATOR

4
Servicing Practices
CHAPITRE 4
PAGE 14
HALIDE HALIDE TORCH TORCH
Using an ultra-violet lamp
Ultra-violet lamp is a method commonly used in large systems
where accessing all joints and connections by soap solution or
electronic detectors is difficult.
By adding an additive dye to the refrigerant, the leak will glow yellow greencolours
when pointed by the ultra-violet lamp, as shown here:
Using additives and ultra-violet lamp
CHAPITRE CHAPITRE 4 4
PAGE PAGE 13 13
Rubber Rubber Hose Hose
(Sni�er) (Sni�er)
Using a halide torch
The halide torch used to be the traditional means of leak detection
with CFCs and HCFCs. A blue flame draws air (and refrigerant) from
the hose and across a copper catalyst.
When refrigerant burns in the presence of this catalyst, the chlorine
components of the refrigerant reacts to cause the flame to change colour
from blue (normal) to green as shown here:
Viewing Viewing
Window Window
Halide torch
DONE
Replaceable Replaceable
Copper Copper Element Element
Adjustment Adjustment
Knob Knob
Since HFCs do not contain chlorine, halide torches will not work
when searching for leaks from HFC system. The same applies to
carbon dioxide (R744), ammonia (R717) and hydrocarbons (R290,
R600a, etc). Obviously, from a safety point-of-view, the halide torch
should not be used to detect hydrocarbons or any other flammable
refrigerants, anyway, or in the presence of other flammable gases.
101
Refrigerant Refrigerant causes causes
a green a green �ame�ame

4
Charging
System charging is adding the proper quantity of refrigerant to
refrigeration system so that it operates as intended. For a given
set of conditions (design conditions) systems have an “optimum”
RE 4 charge – this is the mass of refrigerant that the highest efficiency
and design cooling capacity (or heating capacity, in the case of a
ETRIC CHARGING
heat pump) will be achieved. At off-design conditions, for example,
at a higher or lower ambient temperatures, the optimum charge will
be different. However, it is best to add the specified charge since
this is what the system has been designed to handle.
Servicing Practices
Some systems can handle a wider variation of charge size, in particular,
those with liquid receivers. Direct expansion systems with small
condensers and capillary tube expansion devices tend to be very
sensitive to refrigerant mass and are said to be “critically charged”.
This figure illustrates the sensitivity of a critically charged system, where a
small variation in charge size can greatly reduce the equipment efficiency:
COOLING CAPACITY Qe (kW)
8
6
4
2
0
Example of how
refrigerant charge
affects performance
In all cases, the system data-plate should contain useful information
such as the design refrigerant charge size.
Qe
COP
0,1 0,2 0,3 0,4 0,5
REFRIGERANT CHARGE (kg)
4
3
2
1
0
SYSTEM COP (-)
There are several ways to charge
systems, and the most appropriate
depends upon the local conditions,
the quantity and other factors such
as the type of system.
These methods include:
Volumetric charging by graduated cylinder 4
Mass charging by balance 4
Charging to sight glass 4
Charging according to system performance 4
Electronic charging machines 4
Vapour Refrigerant Charging 4
Liquid refrigerant charging 4
102

4
Servicing Practices
Volumetric charging by graduated cylinder
Using graduated charging cylinder is one of the most popular charging
methods, an example is shown here:
Graduated charging cylinder
It uses a glass tube liquid level indicator, which allows a technician
to transfer refrigerant into a system and measure the amount on
a scale. Some cylinders are electrically heated to speed up the
evaporation and maintain pressure in the cylinder. This process of
electrically heating cylinder is usually done with an electrical insert.
In some cases, the compressor itself is heated, using a heat gun so
the refrigerant and oil will circulate and be purged more easily.
In both cases, it is extremely important that a pressure control relief
valve and thermostat be used to provide the required temperature
and pressure safety controls. The system has a pressure gauge
and hand valve on the bottom for filling the charging cylinder liquid
refrigerant into a system. It also has valve at the top of the cylinder.
This valve is used for charging refrigerant vapour into the system.
Mass charging by balance
CHAPITRE 4
PAGE 16
Using an electronic weight balance, such as the one shown here:
Electronic weight
balance is typically one
of the most accurate
ways to charge
refrigerant. System
charging could be
performed in vapour
or liquid phase. This
is generally done in
smaller systems, which
are more sensitive to
charge size. Therefore it is important to be aware of the additional
refrigerant within the refrigerant hoses, and the artificial weight of
the hoses themselves on the balance reading, so that the actual
mass added to the system is not erroneous.
103

4
Servicing Practices
Charging to sight glass
This method normally applies to larger systems that have a liquid
receiver. Refrigerant is charged into the system, and as it is metered
in, the technician observes the sight glass in the liquid line.
Eventually, once no more bubbles can be seen in the sight glass, the charge
size has approximately been achieved, as shown here:
Charging by sight glass
Bubbles
A Clear Glass
However, as there is always a delay between adding the refrigerant
and the effect on the sight glass, the technician should take extra
time to ensure that the correct charge has been added. It should
also be borne in mind that longer delays between adding refrigerant
and the response of the sight glass occur with larger systems.
As with all other systems, it is important to consider the ambient
temperature and the possibility of adding a little more refrigerant so
that no bubbles appear during warmer/cooler ambient conditions.
In addition, the refrigerant cylinder(s) should be weighed before and
after, and the charged amount checked against the intended charge
or compared against the size of the liquid receiver to ensure that it
will not hydraulically fill during pump-down.
Charging according to system performance
It is possible to charge a system according to the system’s
performance characteristics. This is done by monitoring the suction
pressure, discharge pressure, evaporator superheat and liquid
subcooling out of the condenser.
First, the design performance characteristics are noted: the
ambient temperature, the application temperature (to be cooled
to), the intended superheat and subcooling. From the ambient
temperature and the application temperature, a typical condenser
and evaporator temperature difference is assumed for the
equipment under consideration (say, for example, 8 K), from which
the saturated condensing and evaporating temperatures, and finally
suction and discharge pressures are estimated.
Thermometers are tightly attached to the liquid line and suction
line (using a heat transfer paste and insulated). Refrigerant is
then gradually added into the system and the pressures and
temperatures monitored. As the estimated suction and discharge
pressures are approached, and the design subcooling and
superheat values are achieved, a suitable charge is achieved.
Again, as with the sight glass, there is a delay between adding
refrigerant and the resulting performance characteristics being
achieved, so these performance characteristics should be observed
for some time to ensure that the reading are more or less constant.
104

4
Servicing Practices
Electronic charging machines
During larger-scale manufacturing, equipment tends to be charged
using electronically controlled charging machines. These generally
measure refrigerant into a system using precise mass flow meters,
and are generally accurate to ±0.5g or better.
Vapour refrigerant charging
Vapour refrigerant charging is the process of moving vapour out of
the vapour space of the refrigerant cylinder to the low-pressure side
of the system. Charging while the system is running is acceptable as
cylinder, close the charging cylinder valve and operate the system
for 1-2 minutes until the low-pressure side reading indicates lower
reading than the charging
cylinder.
long as the suction pressure is closely checked during the charging
3 - Continue adding refrigerant by
process. Due to pressure difference consideration, the cylinder
opening the charging cylinder
pressure could become lower than
valve until the proper charge is
system suction pressure during
obtained.
charging. Using a hot water or
servicing charging heaters could
solve this problem. Never use a
brazing torch to heat cylinders.
121 PSIG
OPEN
196 PSIG
CLOSED OPEN
Before connecting any refrigerant
hose to a service or tap valve,
the hose should be briefly purged
(vented) with refrigerant from
In general, follow the same connection
the cylinder to ensure that air
scheme as in evacuation process and
replace the connection with vacuum pump
with the refrigerant charging cylinder as
shown here:
CHAPITRE 4
PAGE 18
VAPOUR REFRIGIRENT CHARGING
SUCTION PRESSURE
50 PSIG
Then:
1 - Open the low-pressure side valve then open refrigerant graduated
charging cylinder valve keeping eye on system pressure and
refrigerant weight scale.
2 - When the pressure has equalised between system and charging
121
PSIG
R-22
Vapour refrigerant charging
and moisture does not enter the
system.
105

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Liquid refrigerant charging
Liquid refrigerant charging is the process of moving liquid refrigerant from
the liquid space of the refrigerant cylinder to the liquid side of the system,
as shown here:
Liquid refrigerant charging usually applies to high refrigerant charge
systems, like large commercial systems and systems with liquid
receivers. Charging liquid refrigerants always requires skill and
caution.
100
PSIG
Liquid refrigerant charging
20 PSIG
CRACKED
40 PSIG
CRACKED
OPEN
196 PSIG
CLOSED
The suction hand-valve is to be used carefully to monitor the liquid
gauge pressure to not exceed 140 kPa (approximately 20 psig)
above suction pressure; when the blue hose (suction line) frost
is observed close to the hand-valve,
check the suction pressure. Repeat until
the desired charge is obtained.
CRACKED
Remember always to make sure that:
• If the refrigerant cylinder does not have a
dip-tube, it should be placed in an upside
down position to guarantee liquid flow.
• Bypassing the low-pressure side control
to avoid shutting off during charging.
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Servicing Practices
Why charge refrigerant blends as liquids?
Refrigerant blends are simply a mixture of different refrigerant
components. If the blend is a zeotropic mixture (i.e. R4xx) and it is
charged as vapour, the refrigerant with the highest vapour pressure
will be charged at a higher proportion than the other component(s).
Charging as a liquid is the only way to guarantee that the blend is
charged within its intended composition.
Fractionation of a refrigerant blend (separation of the individual
components) can occur by removing the refrigerant from the
cylinder as a vapour instead of a liquid. This can potentially lead to
both safety and performance issues. As such, it is recommended
charging all blends in liquid phase only. From a safety standpoint,
a blend with an A1 safety classification – that has been composed
of non-flammable and flammable substances – will remain nonflammable,
even after fractionation has occurred.
Performance may be significantly affected, depending on the
extent of fractionation. If only a small amount of the refrigerant
placed into the system was charged as vapour, the blend may
perform adequately. The performance of systems containing
larger percentages of a blend charged as vapour is more likely to
be affected by fractionation. Typically, more of the high-pressure
components will be found in the system, and less in the cylinder.
Additionally, the refrigerant remaining in the cylinder may also be
compromised. In these cases, it is recommended contact technical
support of the refrigerant supplier.
It is also important to note that if the entire contents of a refrigerant
blend container (full cylinder) are charged into a system as vapour,
it will produce the same effect as charging the entire cylinder
as liquid. Also, certain refrigerant blends are more susceptible
to fractionation than others, and their stated temperature glide
provides an indication of this. For example, fractionation is a greater
concern when working with R409A (high temperature glide, ~ 8 K)
than when working with R410A (a small glide, < 1 K).
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Servicing Practices
Further reading
UK Air Conditioning and Refrigeration Industry Board - Guidelines for
the Use of Hydrocarbon Refrigerants in Static Refrigeration and Air
Conditioning Systems, 2001
4 www.acrib.org.uk/web_images/documents/technical_updates/
Use%20of%20Hydrocarbon%20Refrigerants%20Guidelines.pdf
UNEP DTIE OzonAction – Guidebook for Implementation of Codes of Good
Practice Refrigeration Sector, UNEP, 1998
4 www.unep.fr/ozonaction/information/mmcfiles/2174-e.pdf
UK Institute of Refrigeration Service Engineers’ Section – Bulletin 24 on
Refrigerant Handling and Registration Schemes, 2006
4 www.ior.org.uk/ior_/images/pdf/se/bulletin%2024%20refrigerant%20
handling%20schemes.pdf
UK Institute of Refrigeration Service Engineers’ Section - Bulletin 28 on Leak
checking and Record Keeping under the F Gas Regulations, 2007
4 www.ior.org.uk/ior_/images/pdf/se/bulletin%2028%20f%20gas%20
leak%20checking.pdf
UK Institute of Refrigeration Service Engineers’ Section – Technical
Information on F Gas Refrigerant Handling Training, 2009
4 www.ior.org.uk/ior_/images/pdf/se/SMfgastraining12revised09.pdf
UNEP DTIE OzonAction – Fact Sheet No. 13 on Retrofit of CFCs based
Refrigeration & Air Conditioning Equipment, UNEP
4 www.unep.fr/ozonaction/information/mmcfiles/4766-e-13retrofits.pdf
UNEP DTIE OzonAction - Study on the Potential for Hydrocarbon
Replacements in Existing Domestic and Small Commercial Refrigeration
Appliances, UNEP, 1997
US Environmental Protection Agency – web section on GreenChill Advanced
Refrigeration Partnership which is an EPA cooperative alliance with
the supermarket industry and other stakeholders to promote advanced
technologies, strategies, and practices that reduce refrigerant charges and
emissions of ozone-depleting substances and greenhouse gases
4 www.epa.gov/greenchill
108

5
Retrofitting Content
General retrofitting guidelines 4
General retrofitting process flows 4
Practical cases of retrofitting 4
Further reading 4

5
Summary 5.1. General retrofitting guidelines
This section addresses the approach and working
procedures for changing refrigerants within an
existing system. It provides guidelines for the use
of drop-in refrigerants as well as for retrofitting of
both stationary and mobile systems. It includes a
range of procedures specific to certain types of
common systems.
Upon completion, the technician should be able to:
• Introduce the proper use of drop-in refrigerants
• Identify the procedures for retrofitting
chlorofluorocarbon (CFC) and
hydrochlorofluorocarbon (HCFC) based
systems
• Introduce the procedures for mobile vehicle air
conditioning (MVAC) systems
• Discuss the main aspects involved in retrofitting
domestic refrigerators and MVACs
Retrofitting
Getting started
In general, the retrofit of an equipment or installation means to
substitute older parts for new or modernised ones in order to
improve the performance. In RAC recently, retrofit has come to
mean the procedure of replacing ozone depleting substances
(ODS), or hydrofluorocarbon (HFC) refrigerants in existing plants
with zero ozone depleting potential (ODP) or zero GWP refrigerants.
Retrofitting usually requires modifications such as a change of
lubricant, replacement of expansion device or compressor. If the
conversion does not require such major modifications, the alternate
refrigerant is called a drop-in replacement, or retro-fill process.
Retrofitting from an ODS-using system to an ozone-friendly
refrigerant requires a thorough investigation and study of the system.
Some factors must be taken into account:
• Retrofit the system if it is more cost-effective than replacement.
If a major repair (e.g. compressor change, etc.) or modification
of an ODS using system is necessary it shall be evaluated if
retrofit can be done at acceptable cost.
• Properly working and leak-free systems are not recommended
for retrofit, at least until there is a need to open the refrigeration
system for repair. Properly operating systems can continue
operating for many years without causing harm to the ozone layer.
For older systems that are prone to faults, failures and leaks, it
may be more cost-effective to replace the system rather than
retrofit. In addition, new equipment will be more energy efficient.

5
Retrofitting
• Upon evaluation of a system that requires major repair and
is close to the end of its technical/economical life, consider
replacement if it is more cost effective than retrofitting.
• The safety and environmental properties of alternative refrigerant
to be used, such as flammability, toxicity, ODP and global
warming potential shall be considered.
• Include in the assessment the compatibility of components
and materials in the system, such as elastomers and oil. Also
components like sight glasses and oil separators must be
checked for suitability.
• Assess and examine the operating conditions of the system and
determine the service and its operational history.
If necessary, consult the equipment manufacturer for the recommended
alternative refrigerant and lubricant for the system.
Use of drop-in refrigerants
The phasing-out of ODS refrigerants, and in particular, CFCs in
the RAC sector, has led to the development of new refrigerants
that are often claimed to be direct replacements for the original
ODS refrigerants. These refrigerants vary in compositions; some
are synthetic fluorocarbons, others are natural refrigerants such as
hydrocarbons (HCs), some are single substances, others are blends.
However, it is important to thoroughly investigate any particular
refrigerant that is being considered for use, to ensure that it is a
suitable replacement for the situation under consideration, and that
those working with the refrigerant are fully aware of its implications.
The following should be carried out:
• Check the Material Safety Data Sheets (MSDS) to understand its
safety characteristics
• Request relevant information related to the substance from the
manufacturer of the substance
• Find out whether or not the existing mineral oil needs to be
replaced or not
• Technicians should also look for training on the proper handling
of these new refrigerants.
Hydrocarbons are known to be flammable, although there are
certain concentrations that must be reached prior to explosion
if ignition occurs. That is why education and information
dissemination is very important. Several developing countries are
implementing, with the support of UNEP and other implementing
agencies, training programmes in good practices, and the use
of drop-in refrigerants among other topics are covered in such
courses.
General retrofitting procedures
A generalised procedure should be followed when retrofitting
any refrigeration system with an alternative refrigerant. However,
there may well be specific variations according to the particular
characteristics of the system under consideration and the
refrigerants involved. See the interactive diagram to see how this
flow works for a retrofitting of CFC refrigeration equipment.
111

5
Retrofitting
EXISTING CFC OR
HCFC SYSTEMS
ISOLATE
COMPRESSOR
DRAIN MINERAL
OIL
REFILL WITH
ALTERNATIVE OIL
OPERATE
SYSTEM
DRAIN OIL
IF > 5.0 %
CHECK OIL
CONTAMINATION
The procedures to perform this retrofitting are explained below. If the
ODS refrigerant replacement is being performed with the use of a “dropin”
refrigerant, some of the steps presented may not be necessary. It is
important always to consult the refrigerant manufacturer’s guidelines for
retrofitting and the use of “drop-in” refrigerants. The retrofit to flammable
refrigerants (such as hydrocarbons) must be executed taking into
considerations safety aspects.
IF < 5.0 %
FILL ALTERNATE
REFRIGERANT
REMOVE CFC OR
HCFC
REFRIGERANT
REFILL WITH
ALTERNATIVE OIL
112

5
Retrofitting
General retrofitting process flows
The specific procedures are:
Retrofitting stationary RAC systems 4
MVAC retrofitting procedure 4
Retrofitting stationary RAC systems
Here are the sequential steps involved in a retrofit of a CFC or HCFC based
system.
1 - Record the system performance data prior to retrofit in order to
establish the normal operating conditions for the equipment.
Data should include temperatures and pressure measurements
throughout the system, including the evaporator, compressor
suction and discharge, condenser and expansion device. These
measurements will be useful when adjusting the system during the
retrofit.
2 - Pump down the system and recover the refrigerant before opening
the refrigeration system.
3 - Recovered refrigerant must be stored only in a specified refillable
container or cylinder and properly labelled.
4 - Recovery of refrigerant shall be done using a recovery machine
or a recovery and recycling machine, operated only by a qualified
technician.
5 - Knowing the recommended CFC or HCFC charge size for the system
is helpful. If it is not known, weigh the entire amount of refrigerant
removed. This amount can be used as a guide for the initial quantity
of replacement refrigerant to be charged into the system.
6 - The technician should exert all efforts to ensure the prevention of
refrigerant emissions during the recovery operation.
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5
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7 - If the refrigerant to be added to the system is incompatible with
the existing oil (typically a mineral oil) then it must be removed
(otherwise, this stage can be ignored). Drain and recover the
existing mineral oil charge, measure the quantity and compare
with the recommended oil charge to determine the quantity of oil
left in the system. A major problem with retrofits is removing the
residual mineral oil. This is important because enough mineral oil
is not removed, it can deposit on the evaporator heat exchanger
surfaces, severely degrading performance. Since many small
hermetic compressors do not have oil drains, removal of the
compressor from the system may be necessary for draining the
lubricant. The best point in the system to drain the lubricant is
the suction line of the compressor. Small hand-operated pumps
are available which permit insertion of a tube into the compressor
access port for removal of the mineral oil without removing
the compressor from the system. Remember that most of the
mineral oil must be removed from the system before adding the
replacement lubricant.
8 - Replace all equipment components and accessories that will be
affected by the new alternative refrigerant and the refrigerant oil
suitable for the new alternative refrigerant e.g. expansion valve,
gaskets, filter drier, etc., as recommended by the manufacturer.
Most CFC or HCFC systems with expansion valves will operate
satisfactorily, however, it may be necessary to adjust the superheat.
If the system uses a capillary tube, it will need to be replaced with
one of greater or lesser restriction in order to achieve satisfactory
performance over the complete range of design conditions. It is
recommended that the technician consults with the equipment
manufacturer before replacing the capillary tube.
9 - Charge the system with new and correct amount of alternative
refrigerant oil as recommended by compressor/system manufacturer.
10 - Reinstall the compressor following the standard service practices
recommended by the manufacturer. If an oil pump was used to
remove the oil, reseal the access port.
11 - Run the system while performing the oil change procedure as many
times as necessary until the mineral oil in the system does not
exceed the recommended 5% acceptable level. Test kits are
available from several lubricant suppliers that check for residual
mineral oil content. Generally, it will require about three charges to
get the mineral oil content down to the acceptable level.
12 - Leak test the system with oxygen-free dry nitrogen and observe a
24-hour standing pressure. Make corrections if deemed necessary.
13 - Evacuate system to at least 1000 microns (1 mbar, 29.87 in Hg)
using an appropriate vacuum pump and an electronic vacuum
gauge. Use normal service practices to reconnect and evacuate the
system, to remove air and other non-condensable contaminants.
14 - Charge the system with the appropriate amount of alternative
refrigerant. This can normally be approximated by using the ratio
of liquid densities at the condensing temperature. When charging
the system with alternative refrigerant, use the same charging
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5
Retrofitting
procedures that you would use for CFC or HCFC to ensure optimal
system performance. In general, systems will require a smaller
charge size than those using CFC or HCFC. If the original capillary
tube is used, it will generally be necessary to undercharge the
system to prevent liquid flood back to the compressor. Special
care should be taken when charging with refrigerant blends, as
presented in section 4.
15 - Run the system and charge additional refrigerant if needed until
full-charged. The use of an expansion device not optimised for
the system, such as the original capillary tube, will make the
system more sensitive to charge and/or operating conditions.
As a result, system performance will change more quickly if the
system is overcharged (or undercharged). To avoid overcharging,
it is best to charge the system by first measuring the operating
conditions (including discharge and suction pressures, suction line
temperature, compressor amps, superheat) before using the liquid
level sight glass as a guide.
16 - Monitor the system operation and performance for at least 48 hours
or longer and make necessary adjustment.
17 - Check remaining content of mineral oil with a refractometer or oil
test kit.
18 - Follow the system and/or compressor manufacturer recommendations
as tolerance are dependent on the system and its operating
conditions.
19 - Label the system (as shown in the downloadable data sheet).
After retrofitting the system, label the system components to
identify the refrigerant and specify type of lubricant (by brand name)
in the system. This will help ensure that the proper refrigerant and
lubricant will be used to service the equipment in the future.
115

5
Retrofitting
Retrofitting data sheet
116

5
Retrofitting
MVAC retrofitting procedure
Refer to the manufacturer’s retrofit procedures whenever available.
The following are recommended procedures, specifically for retrofitting R12
MVAC systems to a R134a system:
1 - Check for leaks using a hand-held leak detector (refer also to SAE
J1628: 2003) and set to detect R12 and/or use the soap bubble
test. Make repairs if necessary.
2 - Run the vehicle to obtain suction and discharge pressures, which
should be noted, and check again for leaks.
3 - Recover the entire refrigerant from the system following the
standard procedure for CFC refrigerant recovery and store in a
specified refillable container which is properly labelled.
4 - Remove the compressor from its mounting bracket and drain its
lubricating oil.
5 - Rinse the internal parts by pouring alternative oil for new refrigerant
into the compressor and manually rotating the compressor shaft.
The amount of oil for rinsing is about 50% of the recommended
factory oil charge.
6 - Repeat the oil rinsing procedure as necessary.
7 - Pour the proper amount of alternative refrigerant oil into the
compressor as per the original equipment manufacturer (OEM)
recommendations, and cap the suction and discharge lines until the
system is ready for re-assembly.
8 - Flush the entire system with oxygen-free dry nitrogen and any
cleaning agent not containing an ODS.
9 - Carry out tightness tests for each component for leaks. Repair or
replace if necessary.
10 - Replace the expansion device and the filter drier with ones that are
compatible with the alternative refrigerant.
11 - Change all flare type to O-ring type fittings.
12 - Replace all O-ring seals on pipes and hoses with those approved
for R134a and PAG oils.
13 - Re-install and assemble system components.
14 - Modify the access valves/fittings to accept only the new alternative
refrigerant fittings.
15 - Evacuate system to at least 1000 microns using the appropriate
vacuum pump and an electronic vacuum gauge. Make corrections if
necessary.
16 - Charge the system with the alternative refrigerant (SAE J1657: 2003)
as recommended by the manufacturer whenever possible. Notice
that the optimum charge will change when systems are retrofitted.
17 - Run the vehicle to observe the system operation and check again
for leaks.
18 - Compare the new set of performance data to that obtained when the
system was still using CFC.
19 - Label the system clearly.
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5
Retrofitting
Practical cases of retrofitting –
discussion and procedures
There are a series of specific examples for you to choose from:
Domestic refrigerator retrofit
CFC-based domestic refrigerators and small capacity commercial
refrigeration appliances can be retrofitted with a hydrocarbon
blend (a mixture of propane and isobutane), other commercially
available drop-in blends and R134a. For the hydrocarbon blend
retrofitting, there are typically no changes that need to be done to
the refrigeration system.
However, it is essential that the electrical components associated
with the appliance are checked to determine whether or not they
are potential sources of ignition; if they are they must be replaced
with non-sparking equivalent components, sealed or positioned in
an air-tight enclosure. Such electrical components include relays,
thermostat, door switches and possibly bulb-holders.
Safety is the most important consideration while retrofitting with
HC blends. For retrofitting with R134a, major components like the
compressor, capillary, and filter dryer might need to be changed.
These will make the cost of retrofit very high and uneconomical.
Thus retrofitting with R134a is normally not recommended.
Retrofitting with HC blend or other drop-in blend could achieve a
similar reliability and energy performance as the original equipment.
Retrofitting MVAC systems
MVAC can be retrofitted with R134a, the only accepted refrigerant
by car manufacturers worldwide. However, due to compatibility
issues, the lubricant oil, O-rings, filter dryers and dual pressure
switches may also need to be replaced. The essential point is to
get the system flushed and cleaned and to be made fully leak-tight.
This may be termed as simple or economic retrofit. In this case
there will be slight loss in cooling capacity.
Recently, a more simplified retrofit approach has been adopted: just
adding lubricant (PAG) and charging the system with R134a (80%
of R12 charge) is believed to be compatible for MVAC retrofitting by
some experts in the MVAC sector.
Most car manufacturers have also developed specific retrofitting
kits and procedures for their various models. The OEM retrofit
procedure will provide the greatest assurance of comparable
performance of retrofitted to the original MVAC. But in most cases,
the cost may be relatively high.
For the retrofitted MVAC with R134a, the cooling capacity
and energy efficiency would be slightly reduced depending on
the various factors, but nevertheless, such energy penalty is
acceptable. There is no reported increased failure rate of the
retrofitted R134a MVAC compared with the original produced one.
However, due to the higher R134a operating pressure, a reduction
of cooling performance may occur during city traffic operation.
MVACs are also retrofitted (drop-in mode) with HC blend in some
states of Australia, USA and Canada.
Although, in general, car manufacturers do not condone this option
118

5
Retrofitting
Although, in general, car manufacturers do not condone this option
on safety grounds, there have been many hundreds of thousands
of retrofits for ten or more years without any incidents. However,
if such a retrofit is to be carried out, it must be acknowledged and
accepted by the vehicle owner.
The possibility of cross contamination of refrigerants and improper
system evacuation is generally noticed in MVAC servicing in many
developing countries which leads to poor performance of the
system. In some cases, such bad practices are attributed as a result
of improper retrofitting processes.
Retrofitting of R22 supermarket refrigeration system
The following steps should be followed when retrofitting a supermarket
refrigeration system from R502 or R22 to an HFC refrigerant that is not a
drop-in blend:
1 - Pump-down the R502 or R22 refrigerant charge to the liquid receiver.
2 - Drain as much of the old lubricant from the system as possible,
including from the compressor sump, oil reservoir, and oil separator.
If large amounts of mineral oil remain, it may clog the system and
cause the efficiency of the heat exchangers to decline.
3 - Replace oil filters and filter driers when performing oil changes.
4 - Measure the amount of oil removed, add back an identical quantity
of new oil. Ensure that the new oil chosen is approved by the
compressor manufacturer.
5 - Run the system with the existing refrigerant for at least 24 hours.
Systems running for an extended period may require fewer oil
changes.
6 - Check the system for leaks.
7 - Repeat steps 1 through 4 until the residual oil is less than 5%,
testing using lab analysis or a refractometer.
8 - Evaluate expansion devices using the process described.
9 - Recover the R502 or R22 from the system.
10 - Evacuate the system.
11 - Evaluate the pressure controls, including high pressure cut-outs,
fan cycling controls, and pressure relief devices.
12 - Recharge the system with the new HFC refrigerant.
13 - Check the system for leaks.
Valve rebuilds (for systems built before 1995)
Systems built before 1995 will most likely require new gaskets and O-rings
(elastomers):
1 - Rebuild all Evaporator Pressure Regulators (EPRs).
2 - Rebuild all solenoid valves.
3 - Rebuild hold back valves.
4 - Rebuild heat reclaim valves.
119

5
Retrofitting
5 - Evaluate thermostatic expansion valves (TXVs) and new refrigerant
for proper capacity and superheat. Replace the whole valve or
power head if necessary. Existing R22 valves may be under-sized
for higher mass flow refrigerants R507A, R404A and R422A.
6 - Replace O-rings on the receiver float, and receiver optic switch.
7 - Replace nylon gasket on Roto Lock fittings. Complete steps 6 and 7
prior to pulling a vacuum.
System “Rack”
Replace Schraeder caps and Schraeder cores on the high side. All
Schraeder caps should be brass.
1 - Replace liquid line filters on the conversion date.
2 - Replace suction felts or cores on the conversion date.
3 - Use brass sealing caps on ball valves and compressor service valves.
4 - Set holdback valves on the condenser drain leg.
5 - Set evaporator pressure regulating valves to the manufacturer’s
parameters before setting any superheats.
6 - Set mechanical sub-coolers to the rack manufacturers’ parameters.
Verify the stable operation of the system before setting any
superheats.
7 - Set thermostatic expansion valve superheats to 8–10 K for medium
temperature applications and 5-7 K for low temperature
applications. With blended refrigerants use dew-point temperatures
for superheat measurements.
Retrofitting of R22 chillers
In recent years, R22 water chillers have been converted for use
with a hydrocarbon refrigerant (R290) in some installations in Asian
countries. Procedures used for conversion are similar to the general
procedures.
It must be stressed that it is of utmost importance to ensure that
the correct procedures are followed, that the technicians are trained
correctly and the right safety devices are in place.
Provided these requirements are carried out, a HC charged chiller
will offer a lifetime of service with reduced power consumption and
more efficient cooling.
Certain situations are such that HCs cannot be used for retrofitting chillers,
such as:
• Basement units with no option to ventilate
• Poorly maintained units with existing major problems
• Units adjacent to ignition sources that cannot be isolated
• Large units where the public have access.
120

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Further reading
UNEP DTIE OzonAction – Guidebook for Implementation of Codes of Good
Practice Refrigeration Sector, UNEP, 1998
4 www.unep.fr/ozonaction/information/mmcfiles/2174-e.pdf
UNEP DTIE OzonAction – Fact Sheet No. 13 on Retrofit of CFCs based Refrigeration
& Air Conditioning Equipment, UNEP
4 www.unep.fr/ozonaction/information/mmcfiles/4766-e-13retrofits.pdf
UNEP DTIE OzonAction - Information Paper on Retrofitting with Non-CFC
Substitutes, UNEP, 1994
4 www.unep.fr/ozonaction/information/mmcfiles/3143-e.pdf
Ozone Unit of The Former Yugoslav Republic of Macedonia - Manual for Refrigeration
Service Technicians, 2006
4 www.ozoneunit.gov.mk/eng/doc/Training_manual_for_service_technicians.pdf
UNEP DTIE OzonAction - Training Manual on Good Practices in Refrigeration
– Training Manual, 1994
UNEP DTIE OzonAction - Training Manual on Chillers and Refrigerant Management,
UNEP 1994
121

6
Safety Content
Guidelines Overview of refrigerant safety 4
Important safety procedures 4
Safe handling of flammable refrigerants 4
Safe handling of ammonia (NH3, R717) 4
Safe handling of carbon dioxide (CO2, R744) 4
Further reading 4

6
Summary 6.1. Overview of refrigerant safety
This section covers the relevant safety issues
necessary for working with refrigerants. There is
a general description of the safety implications of
refrigerants, including toxicity, oxygen displacement,
flammability, degradation products, and high
pressure to highlight the major hazards. It includes
a summary of the important safety procedures, such
as personal protection, ensuring a safe working
area, working on a system safety, and how to handle
refrigerant cylinders appropriately.
Primarily aimed at the use of hydrocarbon (HC)
refrigerants, there is also a section detailing the
special requirements for working with flammable
refrigerants, and further guidelines specific to the
use of ammonia (NH3, R717).
Upon completion, the technician should be able to
identify safety procedures for handling refrigerants
and servicing installations.
Safe Refrigerant Handling
The use, storage and handling of all refrigerants present safety hazards.
These hazards may be related to a number of aspects, in that they may:
• be stored at high pressure
• displace oxygen when released in air
• have toxicological effects
• be flammable
• have dangerous decomposition products.
At least one of these characteristics applies to any refrigerant,
and for that reason, a variety of precautions must be followed to
ensure against injury to persons and damage to property. Thus,
safety begins with observing basic precautions and following simple
procedures.
Before using or handling any refrigerant, personnel should be
familiar with the characteristics of the specific substance, reading all
relevant information, which is always available from the supplier and
manufacturer.
It is also important to understand that safety hazards equally apply
to other materials used with refrigerating systems. These include
refrigeration oils, nitrogen, cleaning agents and oxy-acetylene for
brazing.
Whenever handling hazardous substances, a risk assessment
should be carried out, in order to determine what the potential risks

6
Safe Refrigerant Handling
are, what the consequences could be, and most significantly, to
identify the safeguards and precautions to put in place to ensure
that an undesirable event does not occur.
These are considered in the following order:
High pressure fluids 4
Oxygen displacement 4
Toxicological effects 4
Flammability and degradation products 4
High pressure fluids
Most refrigerants are stored under pressure, since they would be
a gas at atmospheric pressure. This presents a number of hazards
that those using refrigerants should be aware of. A fluid being
stored at a pressure several times higher than atmospheric pressure
has the potential to produce a rapid expansion, which is explosive
in nature and can produce shock waves that can injure people and
property. Therefore it is important to ensure that whenever a high
pressure fluid is handled, transferred or released, it is done so under
strict safety procedures.
When a pressurised liquid is exposed to atmospheric pressure,
it will rapidly boil off, thus drawing heat from its surroundings. In
the event that a liquid spill occurs on the skin, this can result in
freezing, thereby causing cell damage and pain. Thus, whenever
handling refrigerants, one must always wear safety glasses and
gloves. If contact with skin should occur, flush the exposed area
with lukewarm (not hot) water. If there is evidence of frostbite, bathe
in lukewarm water, or use other means to warm the skin slowly.
Should eye contact occur, immediately flush with large amounts of
lukewarm water for at least 15 minutes, lifting eyelids occasionally
to facilitate irrigation. Seek medical attention as soon as possible.
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Oxygen displacement
All refrigerants will displace air if released, and when oxygen levels
are depleted, asphyxiation of people (and animals) occurs. Often,
this is manifest by a loss of consciousness without the individual
being aware that it is happening. Furthermore, most refrigerants
are denser than air, which means that rooms below ground, seated
areas, and enclosed spaces are more susceptible. Since most
refrigerants are odourless, occupants may not be aware that oxygen
is being displaced, and may become asphyxiated before they
become aware of this problem.
If a large release of refrigerant occurs, the area should be evacuated
immediately. Good ventilation must be provided in areas where high
concentrations of the vapour could accumulate. Once the area is
evacuated, it must be ventilated using blowers or fans to circulate
the air at floor-level: the lowest point possible. Before performing
maintenance in areas where refrigerants could have accumulated,
a thorough assessment must be carried out in order to determine
whether respiratory protection is required.
It is worth noting that within the field of RAC, there have been more
fatalities associated with oxygen displacement than with any other
aspect. It is essential to use appropriate breathing apparatus to
retrieve someone who has lost consciousness.
Toxicological effects
All refrigerants have some toxicological effects, primarily when
inhaled, but also if they are ingested or come into contact with skin
or other body parts. Normally, the various toxicological effects are
considered according to the potentially dangerous concentrations,
and for each substance, maximum concentrations are issued.
Many countries tend to have their own criteria, definitions and allowable
concentrations. However, across most countries, there are two values, which
are based on exposure in the workplace:
• A long-term exposure limit, based on an 8-hour time weighted
average reference period, and
• A short-term exposure limit, based on a 15-minute time
weighted average reference period
The long-term exposure limit represents the allowable concentration
that workers can be constantly exposed to during their working
hours, without any adverse effects. The short-term exposure limit
applies to the maximum concentrations that can be tolerated by
most people in the event of a catastrophic release, where they
need to make an emergency escape. Concentrations are normally
specified in parts per million (ppm) or milligramme (mg) per m3.
These exposure limits have different names in different countries.
For example, in the UK they are termed the Workplace Exposure
Limits (WEL), in Japan, France and Germany they are Occupational
Exposure Limits (OEL), in the USA they are Permissible Exposure
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Limits (PEL), and the European Union employs two different values:
Indicative Occupational Exposure Limit Values (IOELV) and Binding
Occupational Exposure Limit Values (BOELV), depending upon the
circumstances.
In general, it is important to check whether the products one
intends to work with can be safely used in all of their considered
applications and handled in accordance with manufacturer
information. Whilst the toxicity of most refrigerants is low, the
possibility of injury or death exists in unusual situations or if they are
deliberately misused.
Exposure to refrigerant concentrations above the recommended
exposure levels can result in loss of concentration, drowsiness,
cardiac arrhythmia, and other symptoms, that can all lead to
fatality. The allowable exposure levels for some of the alternative
refrigerants are lower than those of the chlorofluorocarbons (CFCs).
As mentioned before, skin should be protected; many fluorinated
refrigerants and ammonia can irritate the skin and eyes.
Inhalation of concentrated refrigerant vapour is dangerous and
can be fatal. If inhaled, the victim should be moved to an area with
fresh air. If they are not breathing, they should be given artificial
respiration, and if breathing is difficult, give oxygen. It is important
to avoid stimulants, and do not give them adrenaline (epinephrine)
because this can complicate possible effects on the heart. Medical
help must be sought urgently.
Flammability and degradation products
A number of refrigerants are flammable under atmospheric
conditions. Flammability means that if ignited with a flame or spark,
they can sustain combustion. All hydrocarbon refrigerants are
flammable, as are some hydrofluorocarbon (HFC) refrigerants. The
refrigerants table in section 2 identifies those refrigerants which are
flammable. The refrigerant supplier will also provide information
relating to a refrigerants’ flammability.
Refrigerants table in Chapter 2 4
Depending upon the characteristics of a particular substance,
the consequences of ignition can be severe, and therefore it is
essential to take the appropriate precautions whenever designing,
constructing or working on a system that uses flammable
refrigerants.
Whilst many CFC, hydrochlorofluorocarbons (HCFCs) and HFC
refrigerants are not flammable under normal conditions, they can
become flammable when under pressure and mixed with air and/or
oil. Because of this potential, the refrigerants should never be mixed
with air in tanks or supply lines, or allowed to accumulate in storage
tanks, and sources of ignition should also be avoided.
Even if the conditions are such that CFC, HCFC and HFC
refrigerants are non-flammable, these substances will decompose
at high temperatures such as those associated with gas flames or
electric heaters.
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The compounds that result under these circumstances always
include hydrofluoric acid. If the compound contains chlorine,
hydrochloric acid will also be formed, and if a source of water, (or
oxygen), is present, a smaller amount of phosgene will be formed.
Halogen acids have a very sharp, stinging effect on the nose and
if they are detected, the area should be evacuated until the air has
been cleared of decomposition products.
Important safety procedures
Before working with a refrigerant, information and appropriate rules of
conduct should be sought:
• Personnel who handle refrigerants should be properly trained in
their safe use and handling.
• Personnel should have reviewed the material safety data sheet
(MSDS) for the refrigerant used.
• Personnel must not smoke, braze, or weld when refrigerant
vapour is present. Refrigerants can either ignite, or decompose
to produce harmful, corrosive and toxic substances when
exposed to an open flame or hot surface.
There are a number of aspects that technicians should always be aware of
whilst handling refrigerants.
Personal protection 4
Ensuring a safe work area 4
Safe working with a system 4
Handling refrigerant cylinders 4
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Personal protection
Prior to working on a system, or handling refrigerant, technicians should be
adequately equipped with the appropriate safety equipment:
• Check the MSDS for the refrigerant, lubricant and other
substances in order to determine the proper level of protection
required.
• Wear safety goggles and gloves at all times when handling
refrigerants or servicing a refrigeration system.
Wear the proper respiratory
protection while working
with refrigerants. Inhalation
of refrigerants can cause
intoxication, induce anaesthetic
effects, cause stumbling,
shortness of breath, tremors,
convulsions, and the heart to
cease functioning properly and
may be fatal.
Ensuring a safe work area
Before working with a refrigerant, the local area must be prepared
accordingly in case of an accidental release:
• Proper ventilation or respiratory protection is required for
any work on equipment in an enclosed area where a leak is
suspected.
• Always ventilate or test the atmosphere of an enclosed
area before beginning work. Many refrigerants which may
be undetectable by human senses are heavier than air and
will replace the oxygen in an enclosed area causing loss of
consciousness.
• Evacuate the area if a large spill occurs. Return only after the
area has been properly ventilated.
• Always ventilate the work area before using open flames.
Safe working with a system
When working on a system, several basic considerations should be borne in
mind:
• Always check for the correct operating pressure of the
refrigerant used. Use gauges to monitor the system pressure.
• Charge the refrigerant into the low side of the system to avoid
damaging the compressor, or causing the system to rupture.
• Refrigerant oil in a hermetic compressor is often very acidic
causing severe burns. Avoid skin contact with this oil.
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• Never cut or drill into any refrigeration system, without first
removing the refrigerant. The high pressure refrigerant will be
released rapidly and have serious consequences.
• Ensure that all refrigerant is removed from the system and the
pressure has been brought up to atmospheric pressure with
oxygen-free dry nitrogen before disassembling a system.
• When soldering, brazing, or welding on refrigeration lines,
the lines should be continuously purged with low pressure
oxygen-free dry nitrogen. Cylinders, transfer lines and other
equipment used with refrigerants should not be exposed to high
temperature sources, such as welding, brazing and open flames.
• Following work, the system parts should only be pressure tested
with nitrogen.
• Never pressurise systems or vessels containing refrigerants with
air for leak testing or any other purpose.
• Before transferring refrigerant, verify that the hoses are properly
connected to the system and cylinders.
• Open cylinder valves, hose valves and manifold valves slowly
and steadily.
• Verify that the system has been completely evacuated with a
vacuum pump before cutting any lines.
• Before welding or brazing, evacuate the equipment and then
break the vacuum with oxygen free dry nitrogen. Do not perform
any repair on pressurised equipment.
• Whenever using nitrogen cylinders, ensure that the correctly
rated regulator is used, and the setting does not exceed the
maximum working pressure of the system being worked on.
Handling refrigerant cylinders
Refrigerant cylinders tend to be transported widely and subjected to a
variety of conditions. For these reasons it is important to ensure that they
are handled carefully to avoid severe consequences:
• Always store and transport refrigerant cylinders in upright position
to keep the pressure relief valve in contact with the vapour space.
• Do not throw or drop refrigerant cylinders during transportation,
and never permit them to strike each other violently.
• Do not apply direct heat to refrigerant cylinder while charging a
system to maintain inside pressure; a warm water bath should
be used for that purpose.
• Keep the cylinder cap on the cylinder at all times unless the
cylinder is in use.
• When refrigerant is discharged from a cylinder, immediately
weigh the cylinder, and record the weight of the refrigerant
remaining in the cylinder.
• Ensure only regulators and pressure gauges designed for the
particular refrigerant in the cylinder are used, and do not use
different refrigerants in the same regulator or gauges. Never
attempt to repair cylinders or valves.
• Never use a lifting magnet or a sling. A crane may be used when
a safe cradle is provided to hold the cylinders.
• Never use cylinders for any other purpose than to carry refrigerants.
• Never tamper with cylinder valves or pressure relief devices, or
other safety devices.
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• Never force connections that do not fit. Ensure the cylinder valve
outlet threads are the same as what is being connected to it.
• Cylinders should always be stored
upright, and larger cylinders should be
chained in place to avoid falling as shown
here:
• It is preferable to store cylinders
within a secured cage.
CHAPITRE 6
PAGE 08
• Cylinders stored in the open must be
protected from extremes of weather
and direct sunlight.
R-134a
R-134a
125lbs
R-401A
125lbs 125lbs
• Never expose cylinders to continuous
dampness, salt water, or spray. They
should be kept in a cool, dry and properly ventilated storage
area, away from heat, flames, corrosive chemicals, fumes and
explosives, and be otherwise protected from damage.
• Cylinders should never be exposed to temperature above 52°C.
• Store full and empty cylinders apart to avoid confusion. They
must be clearly marked.
• Store cylinders secured and upright in an area where they will
not be knocked over or damaged, and never store cylinders
near elevators or gangways, or near highly flammable
substances.
• Refrigerant cylinders should never be filled over 80% of their capacity
because the liquid expansion may cause the cylinder to burst – as
shown in this illustration:
• Always check the refrigerant number before charging to avoid
mixing refrigerants.
• Check the cylinder stamp to ensure the cylinder is safe. Inspect
refrigerant cylinders regularly. Do not use the cylinders if they
show signs of rust, distortion, denting, or corrosion.
• Never refill disposable cylinders with anything. Do not use
disposable refrigerant cylinders as compressed air tanks.
CHAPITRE 6
PAGE 09
• Any evidence of a leak, visual or by a leak detector must be
corrected immediately, by either stopping the leak or transferring
all products from the leaking container into a secure container to
allow for repairs.
Cylinder Temp.
Starting with
cylinder 75%
full by volume
Cylinder Temp.
Starting with
cylinder 85%
full by volume
NEVER
21°C 38°C 54°C 66°C
75%
Space
21°C 38°C 54°C 66°C
85%
Space
80%
Space
95%
Space
90%
Space
100%
Effect of temperature on liquid volume inside a cylinder
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Safe handling of flammable refrigerants
Whilst hydrocarbons are very good refrigerants, their flammability
means that their use need to be considered carefully. Safety
and legislative issues need to be fully understood. The use of
hydrocarbons has been widespread in the European domestic
refrigeration market since the mid-nineties.
The following steps will help:
Manuals and instructions 4
General Approach to hydrocarbon refrigerant handling 4
Safety check of the working area 4
Safety check of the refrigeration equipment 4
Safety checks to electrical devices 4
Detection of hydrocarbon refrigerants 4
Breaking into a system and removal of refrigerant 4
Charging of refrigerant 4
Cylinder handling 4
Storage of cylinders 4
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Manuals and instructions
Before handling hydrocarbon refrigerants be aware of detailed
information to be provided in manuals for the installation,
service and operation (be they separate or combined manuals).
The manuals will include all the relevant information about the
equipment, such as the maximum refrigerant charge, the minimum
rated airflow if required, the minimum floor area of the room or
any other special requirements, as well as all the corresponding
warnings. Importantly, they must all provide the necessary
information and instructions for the correct handling of flammable
refrigerants and associated equipment, refrigerant detection,
charging, equipment decommissioning, removal, recovery and
storage of the refrigerant, and aspects related to ensuring the
integrity of the protection for electrical components.
Only competent professionals trained in the use of flammable
refrigerants are permitted to open equipment housing or to break
into the refrigerant circuit, and the maintenance and repair requiring
the assistance of another skilled person should be carried out under
the supervision of the competent individual.
General Approach to hydrocarbon refrigerant handling
Any equipment used in the process of repair must be suitable for
use with flammable refrigerants.
All tools and equipment (including measuring equipment) are to be checked
for suitability for working on the equipment, particular attention is to be
paid to the selection of:
• Refrigerant recovery units
• Refrigerant leak testing units
• Electrical test meters
• Refrigerant recovery cylinders
• Portable lighting.
If the installation permits, it is recommended that the equipment
be removed from its existing position to a controlled workshop
environment suitable for the type of repair where work can be
conducted safely.
Safety check of the working area
Prior to beginning work on systems containing hydrocarbon
refrigerants, safety checks are necessary to ensure that the risk of
ignition is minimised.
For repair to the refrigerating system prior to conducting work on the
system, the following precautions shall be complied with:
• Work shall be undertaken under a controlled procedure so as to
minimise the risk of a flammable gas or vapour being present
while the work is being performed.
• All maintenance staff and others working in the local area should
be instructed as to the nature of work being carried out.
• Work in confined spaces must be avoided. The area around the
workspace is to be sectioned off.
• Ensure that the conditions within the area have been made safe
by the control of flammable material.
• The area shall be checked with an appropriate refrigerant
detector prior to and during work to ensure that the technician
is aware of potentially flammable atmospheres. Ensure that the
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leak detection equipment being used is suitable for use with
flammable refrigerants, i.e. non-sparking, adequately sealed or
intrinsically safe.
• If any hot work is to be conducted on the refrigeration equipment
or any associated parts, appropriate fire extinguishing equipment
shall be available to hand. Have a dry powder or carbon dioxide
fire extinguisher adjacent to the charging area.
• No person carrying out work in relation to a refrigeration system
which involves exposing any pipe work which contains or has
contained flammable refrigerant shall use any sources of ignition
in such a manner that it may lead to the risk of fire or explosion.
• All possible ignition sources, including cigarette smoking, should
be sufficiently far away from the site of installation, repairing,
removing and disposal during which flammable refrigerant can
possibly be released to surrounding space. Prior to work taking
place, the area around the equipment is to be surveyed to
establish any flammable hazards or ignition risks. Display “No
Smoking” signs.
• Ensure that the area is in the open or that it is adequately
ventilated before breaking into the system or conducting any
hot work. A degree of ventilation should continue during the
period that the work is carried out. The ventilation should
safely disperse any released refrigerant and preferably expel it
externally to the atmosphere.
Safety check of the refrigeration equipment
Where electrical components are being changed, they are to be
“fit for purpose”, and to the correct specification. At all times
the manufacturer’s maintenance and service guidelines are to
be followed. If in doubt consult the manufacturer’s technical
department for assistance.
The following checks should be applied to installations using flammable
refrigerants:
• That the charge size is in accordance with the room size within
which the refrigerant containing parts are installed. Hydrocarbon
charge sizes are typically 40% to 50% of CFC, HCFC and HFC
charge sizes.
• That ventilation machinery and outlets are operating adequately
and not obstructed.
• Confirm the operation of equipment such as refrigerant leak
detectors and mechanical ventilation systems.
• If an indirect refrigerating circuit is being used, the secondary
circuit should be checked for the presence of refrigerant.
• Ensure that marking to the equipment continues to be visible and
legible. Marking and signs that are worn should be corrected.
• Check that refrigeration pipe or components are not installed in
a position where they are likely to be exposed to any substance
which may corrode refrigerant-containing components, unless
the components are constructed of materials which are
inherently resistant to being corroded or are suitably protected
against corrosion.
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Safety checks to electrical devices
Repair and maintenance to electrical components shall include
initial safety checks and component inspection procedures. If a
fault exists that could compromise safety, then no electrical supply
should be connected to the circuit until it is satisfactorily dealt with.
If the fault cannot be corrected immediately but it is necessary to
continue operation, an adequate temporary solution shall be used,
but this must be reported to the owner of the equipment so all
parties are aware.
Initial safety checks should be as follows:
• Ensure that capacitors are discharged. This should be done in a
safe manner to avoid the possibility of sparking.
• Do not work on “live” electrical components and wiring whilst
charging, recovering or purging the system.
• Continuity of earth bonding.
During repairs to sealed components, all electrical supplies must
be disconnected from the equipment being worked upon prior to
any removal of sealed covers, etc. If it is absolutely necessary to
have an electrical supply to equipment during servicing, then a
permanently operating form of leak detection shall be located at
the most critical point to forewarn the individual of a potentially
hazardous situation.
For repairs to sealed components, particular attention should be paid to the
following:
• Ensure that by working on electrical components, the casing is
not altered in such a way that the level of protection is affected.
This should include damage to cables, too many connections,
terminals not made to the original specification, damage to
seals, incorrect fitting of glands, etc. This includes the secure
mounting of the apparatus.
• Ensure that seals or sealing materials have not degraded such
that it is no longer serving the purpose of preventing the ingress
of flammable atmospheres.
• Replace only with parts specified by the manufacturer. Other
parts may result in the ignition of refrigerant in the atmosphere
from a leak.
Check that cabling will not be subject to wear corrosion, excessive
pressure, sharp edges or any other adverse environmental effects.
This should also take into account the effects of ageing or continual
vibration from sources such as the compressor or fans.
Detection of hydrocarbon refrigerants
Under no circumstances should potential sources of ignition be
used in the searching or detection of refrigerant leaks. A halide
torch (or any other detector using a naked flame) must not be used.
The following leak detection methods can be used on systems containing
hydrocarbons:
• Electronic leak detectors may be used to detect hydrocarbons,
but the sensitivity may not be adequate, or may need calibration
(detection equipment should be calibrated in a refrigerantfree
area). Ensure that the detector is not a potential source of
ignition and is suitable for hydrocarbon refrigerants.
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• Leak detection equipment should be set at a percentage of the
LFL of the refrigerant and should be calibrated to the refrigerant
employed and the appropriate percentage of gas (25%
maximum) is confirmed.
• Leak detection fluids are suitable for use with hydrocarbon
refrigerants but the use of detergents containing chlorine should
be avoided as the chlorine may react with the refrigerant and
corrode the copper pipework.
• Oil additives such as those used in fluorescent leak detection
systems will operate with hydrocarbons.
• If a leak is suspected from a hydrocarbon refrigerant system all
naked flames should be removed or extinguished.
If a leakage of refrigerant is found which requires brazing, all of
the refrigerant shall be recovered from the system, or isolated (by
means of shut off valves) in a part of the system remote from the
leak. Oxygen Free Nitrogen (OFN) should then be purged through
the system both before and during the brazing process.
Breaking into a system and removal of refrigerant
When breaking into the refrigerant circuit to make repairs - or for
any other purpose – conventional procedures are used. However, it
is important that best practice is followed since flammability is now
a consideration.
The following procedure shall be adhered to:
• remove the refrigerant
• purge the circuit with inert gas
• evacuate
• purge again with inert gas
• open the circuit by cutting or brazing.
The refrigerant charge should be recovered into the correct recovery
cylinders. The system is then to be “flushed” with OFN to render the
unit safe; this process may need to be repeated several times. Do
not use compressed air or oxygen for this task.
Flushing is achieved by breaking the vacuum in the system with
OFN and continuing to fill until the working pressure is achieved,
then venting to the atmosphere, and finally pulling down to a
vacuum. This process is repeated until the technician is satisfied
that no hydrocarbons are within the system.
When the final OFN charge is used, the system can be vented
down to atmospheric pressure to enable work to take place. This
operation is absolutely vital if brazing operations on the pipe work
are to take place. Ensure that the outlet for the vacuum pump is not
close to any ignition sources and ventilation is available.
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Charging of refrigerant
The charging of refrigeration systems with hydrocarbon refrigerants
is similar to those using halocarbon refrigerants. As with all blend
refrigerants, hydrocarbon refrigerant blends should also be charged
in the liquid phase in order to maintain the correct composition of
the blend.
The following additional requirements should be adhered to:
• Ensure that contamination of different refrigerants does not
occur when using charging equipment. Hoses or lines are to
be as short as possible to minimise the amount of refrigerant
contained in them.
• Cylinders must be kept upright.
• Charge the refrigerant in the liquid phase.
• Ensure that the refrigeration system is earthed prior to charging
the system with refrigerant.
• Label the system when charging is complete. The label should
state that hydrocarbon refrigerants have been charged into the
system and that it is flammable. Position the label in a prominent
position on the equipment.
• Extreme care shall be taken not to overfill the refrigeration
system. Hydrocarbon charge sizes are typically 40% to 50% of
CFC, HCFC and HFC charge sizes.
• The system must be leak tested on completion of charging.
Cylinder handling
Safe cylinder handling differs little from other refrigerant cylinders which
are as follows:
• Do not remove or obscure the official labelling on a cylinder.
• Always refit the valve cap when the cylinder is not in use.
• Use and store cylinders in an upright position.
• Check the condition of the thread and ensure that it is clean and
not damaged.
• Store and use cylinders in dry, well-ventilated areas remote from
fire risk.
• Do not expose cylinders to direct sources of heat such as steam
or electric radiators.
• Do not repair or modify cylinders or cylinder valves.
• Always use a proper trolley for moving cylinders even for a short
distance – never roll cylinders long the ground.
• Take precautions to avoid oil, water and foreign matter entering
the cylinder.
• If it is necessary to warm the cylinder, use only warm water or
air, not naked flames or radiant heaters. The temperature of the
water or air must not exceed 40°C.
• Always weigh the cylinder to check if it is empty – its pressure
is not an accurate indication of the amount of refrigerant that
remains in the cylinder.
• Use only dedicated recovery cylinders for the recovery of
hydrocarbon refrigerants.
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Storage of cylinders
Refrigerant cylinders should be stored taking into account the following
precautions:
• Cylinders should be preferably stored outside and never stored
in residential premises.
• Cylinders may be stored in commercial and industrial premises
according to the following guidelines for storage.
• Quantities stored are to be restricted to no more than 70 kg and
stored in specific dedicated areas or cages.
• Access to storage areas restricted to ‘authorised persons
only’, and such places shall be marked with notices prohibiting
smoking and the use of naked flames.
• Cylinders containing hydrocarbon refrigerants should be stored
at ground level, never in cellars or basements. Cylinders should
be readily accessible, and stored upright.
Safe handling of ammonia (NH3, R717)
The safety classification of R717 is lower flammability and higher
toxicity. In general, it is fairly difficult to ignite, and even then, it
does not easily sustain a flame. Nevertheless, due to its flammable
nature, it should be treated as such.
Safe handling of flammable refrigerants 4
R717 is also a higher toxicity refrigerant, and for this reason, extra
caution should be taken. Because of its affinity for water, R717
will attack any moist body parts such as armpits, eyes, throat and
groin at relatively low concentrations. Its strong odour is detectable
by most people at 2 to 5 ppm. Low temperatures increase the
sensitivity to the presence of ammonia. High humidity reduces the
level at which ammonia is perceived.
You can review:
Recommendations for exposure 4
Safety procedure guidelines 4
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Physiological effects of different R717 concentrations (IOR, 2005)
Concentration Effect on unprotected human body Exposure Limits
20 ppm
Smell readily detected by most
people
25 ppm HSE long term exposure limit
35 ppm HSE short term exposure limit
50 ppm
70 ppm
400 – 700 ppm
1700 ppm
2000 – 5000 ppm
Smell is distinctive and may be
irritating
No dangerous effects on healthy
people
Immediate irritation to eyes, nose,
throat and respiratory system.
Severe coughing, cramp, serious
irritation to nose, eyes, throat and
respiratory system
Severe coughing, cramp, serious
irritation to nose, eyes, throat and
respiratory system
Unlimited
8hrs per day 5 days per
week
15mins per day not more
than 1 hour per week
Do not stay longer than
necessary
Leave the area
Under normal circumstances
no serious injury in 1 hour
30 mins exposure can lead
to serious injury
30 mins exposure can lead
to death
5000 ppm Respiratory spasm, rapid asphyxia Lethal within a few minutes
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Recommendations for exposure
If you do come into physical contact with ammonia, you should administer
the following first aid, and seek immediate medical attention:
Skin contact: Remove contaminated clothing. Drench with large
quantities of water and continue to wash affected skin areas for
at least 20 – 30 minutes, and use safety shower if available. In the
case of freeze burns, clothing may adhere to the skin, in which case,
immerse the affected area in comfortably warm water to defrost.
Eye contact: Flood eyes with clean tap water for at least 20 – 30
minutes followed by immediate medical attention.
Ingestion: Rinse mouth with water and give plenty to drink. Do not
induce vomiting but seek medical attention immediately.
Inhalation: Remove the patient to fresh air immediately. Remove
contaminated clothing and keep the patient warm and rested.
Seek medical assistance immediately. The patient must be kept
under observation for at least 48 hours after exposure as delayed
pulmonary oedema may develop.
Safety procedure guidelines
In order to be able to respond to a release of R717, the following should be
adhered to:
• Escape routes should be known and must be free from
obstacles.
• Suitable personal protective equipment including gloves and
goggles must be worn at all times.
• Ensure that breathing apparatus and/or respirator masks are
available and close to hand. It is good practice for engineers to
wear their respirator mask loose around the neck when carrying
out any works other than visual inspections.
• Fire-fighting equipment should be accessible within the
machinery room.
• Work should only commence on equipment after carrying out a
full and approved risk assessment plus a method statement so
that “everyone” is aware of what works are being undertaken
and by whom.
• Only qualified or experienced engineers should work on
ammonia systems.
• If carrying out works other than routine checks then engineers
should work in pairs.
Due to the widespread use of ammonia throughout industry, many
countries have specific laws relating to its use and handling.
It is important to check national regulations with respect to the following:
• General health and safety legislation
• National and international refrigeration safety standards
• Codes of practice issues by trade bodies and institutes
• Rules for storage and handling of hazardous materials.
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Safe Refrigerant Handling
Safe handling of carbon dioxide (CO2,
R744)
CO2 is a relatively safe refrigerant compared to
natural and artificial working fluids. It is classified
in group A1, which are the refrigerants with low
toxicity and non-flammable, according to ASHRAE
Handbook-Fundamentals and ISO 817: 2005,
which is the international standard for refrigerant
safety classification. A1 is the group that contains
the refrigerants that are least hazardous and
without an identified toxicity at concentrations
below 400 ppm. Naturally, CO2 exists in the
atmosphere at concentrations around 350 ppm
and for concentrations between 300 and 600 PPM
people do not usually notice the difference.
According to ASHRAE, a CO2 concentration
of 1000 ppm is the recommended limit to satisfy comfort for the
occupants, where in a CO2 controlled ventilation system fresh air
should be supplied so that the CO2 concentration level will not
exceed this value. This is the case of an application when a small
CO2 generation rate is expected due to different human activities.
However, in the case of high leakage rate that might occur in
supermarket space or in the machine room, the consequences of
serious health hazards, such as suffocation, must be taken into
account.
Different concentrations of CO2 and the expected health consequences
(GTZ2008)
1 - The Occupational Safety and Health Administration (OSHA) revised
Permissible Exposure Limit (PEL): Time-Weighted Average (TWA)
concentration that must not be exceeded during any 8 hour per day
40 hour per week.
2 - Threshold Limit Value (TLV): TWA concentration to which one may
be repeatedly exposed for 8 hours per day 40 hours per week
without adverse effect.
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Safe Refrigerant Handling
3 - Short Term Exposure Limit (STEL): a 15-minute TWA exposure that
should not be exceeded at any time during a workday.
4 - National Institute for Occupational Safety and Health (NIOSH) revised
Immediately Dangerous to Life or Health (IDLH) value.
5 - IDLH: maximum level for which one could escape within 30
minutes without any escape-impairing symptoms or any irreversible
health effects.
CO2 has a main drawback of not being self-alarming by lacking a
distinctive odour or colour. This implies that facilities where CO2
may leak must be equipped with sensors that trigger alarm when
the concentration level exceeds 5000 ppm, above which CO2
concentration may have effect on health. CO2 is heavier than air
and therefore will collect close to the floor when it leaks; thus, the
sensors and the ventilators in the space where CO2 might leak
should be located close to the floor.
In case of component rupture, the fact that CO2 has relatively
high operating pressure compared to other refrigerants raises
questions concerning the hazards of blast effects, shocks and
flying fragments. The sudden depressurization leads to explosive
vaporization and a transient overpressure peak that may burst the
vessel. The explosive energy per kg for CO2 is high compared
to R22. However, when the comparison is made for ductless
residential air conditioning system with equal cooling or heating
capacities and similar efficiencies then owing to the smaller
volume and refrigerant charge of the CO2 system, the actual
explosive energies are in the same range. In the supermarket
system the expected explosive energy may be higher than the
cases with conventional systems. This is due to the presence of
the accumulation tank in most of the CO2 system solutions which
increases the system’s charge and volume.
However, the explosive energy is more of a concern with systems
where the occupants are close to the system’s components; such
as mobile air conditioning (MAC) and residential air conditioning.
In supermarket systems the high pressure components are in
the machine room and the distribution lines are usually kept in a
distance from the consumers.
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Safe Refrigerant Handling
Further reading
UK Institute of Refrigeration Service Engineers’ Section - Datasheet 16
“Ammonia Safety”, 2005
UK Institute of Refrigeration Service Engineers’ Section – Assessment for Save
Handling of Refrigerants, 2006
4 www.ior.org.uk/ior_/images/pdf/serv%20matters%209-%20ref%20assessments.pdf
European Fluorocarbon Technical Committee – an association of fluorocarbon
producers in Western Europe under the umbrella of CETIC, References on
Refrigeration Fluids and Safety
4 www.fluorocarbons.org/en/debate/safety_aspects/references_on_refrigeration_fluids_and_safety.html
UK Air Conditioning and Refrigeration Industry Board - Guidelines for the Use
of Hydrocarbon Refrigerants in Static RAC Systems
4 http://www.acrib.org.uk/web_images/documents/technical_updates/Use%20of%
20Hydrocarbon%20Refrigerants%20Guidelines.pdf
Air Conditioning and Refrigeration Guide
4 http://www.air-conditioning-and-refrigeration-guide.com/
UK Institute of Refrigeration Service Engineers’ Section - Safety Code of Practice
for Ammonia Refrigeration Systems, 2009
4 http://www.ior.org.uk/
142

Glossary
Glossary
Absolute pressure
The actual pressure, where a true vacuum is the zero value, and so
atmospheric pressure is approximately 1.013 bar.
Accumulator
A vessel capable of holding liquid refrigerant and permanently connected
between the exit of the evaporator and suction of the compressor.
Air-conditioning
It is the process of controlling temperature, humidity, composition, and
distribution of air for the purpose of human comfort or for special technical
need of a industrial process (pharmaceutical, textile, etc.) or other application.
Article 2 countries
Parties to the Montreal Protocol that do not operate under Article 5. “Article 2
countries” refer to developed countries.
Article 5 countries
Developing country Parties to the Montreal Protocol whose annual per capita
consumption and production of ozone depleting substances (ODS) is less
than 0.3 kg to comply with the control measures of the Protocol, are referred
to as Article 5 countries. Currently, 147 of the 196 Parties to the Montreal
Protocol meet these criteria. Article 5 countries are eligible to receive technical
and financial assistance from the Multilateral Fund Secretariat, as per Article
10 of the Protocol.
Atmospheric lifetime
A measure of the average time that a molecule remains intact once released
into the atmosphere.
Atmospheric pressure
Also known as barometric pressure. It is the pressure exerted by the
atmosphere above the surface of the Earth. Standard sea level pressure is a
unit of pressure and, by definition, equals 1 atmosphere (atm) or 101.35 kPa.
Azeotrope
A blend consisting of one or more refrigerants of different volatilities that does
not appreciably change in composition or temperature as it evaporates (boils)
or condenses (liquefies) under constant pressure. Refrigerant blends assigned
an R5xx series number designation by ISO 817 are azeotropes.
Banks
The total amount of substances contained in existing equipment, chemical
stockpiles, foams and other products not yet released to the atmosphere.
Blends (mixtures)
A mixture of two or more pure fluids. Blends are used to achieve properties
that fit many refrigeration purposes. For example, a mixture of a high pressure
and a low pressure substance mixed in order to match the pressure of
another substance. Blends can be divided into two categories: azeotropic,
and zeotropic blends.
Boiling point
The temperature of a liquid at the point it starts to vaporize (see NBP).
Brazed joint
A joint obtained by the joining of metal parts with alloys which melt at
temperatures in general higher than 450°C but less than the melting
temperatures of the joined parts
Bubble point
Liquid saturation temperature of a refrigerant at the specified pressure; the
temperature at which a liquid refrigerant first begins to boil.
Cascade system
Two or more independent refrigeration circuits where the condenser of one
system rejects heat directly to the evaporator of another.
Chlorofluorocarbons (CFCs)
Halocarbons containing only chlorine, fluorine and carbon atoms. CFCs are
both ozone depleting substances and greenhouse gases.
Climate change
Climate change refers to a statistically significant variation in either the mean
state of the climate or in its variability, persisting for an extended period (typically
decades or longer). Climate change may be due to natural internal processes or
143

Glossary
external forcing, or to persistent anthropogenic changes in the composition of
the atmosphere or in land use. Note that Article 1 of the Framework Convention
on Climate Change (UNFCCC) defines ‘climate change’ as ‘a change of
climate which is attributed directly or indirectly to human activity that alters the
composition of the global atmosphere and which is in addition to natural climate
variability, observed over comparable time periods’. The UNFCCC thus makes a
distinction between ‘climate change’ attributable to human activities altering the
atmospheric composition, and ‘climate variability’ attributable to natural causes.
Coefficient of Performance (COP)
A measure of the energy efficiency of a refrigerating system. The ratio of
useful effect (heat) to the work supplied. The useful effect is the cooling rate in
the case of RAC systems, and it is the heating rate in the case of heat pumps.
The COP is primarily dependant on the working cycle and the temperature
levels (evaporating/ condensing temperature) as well as on the properties of
the refrigerant, system design and size.
Coil
A part of the refrigerating system constructed from bent or straight pipes or
tubes suitably connected and serving as a heat exchanger (evaporator or
condenser).
Competence
The ability to perform satisfactorily the activities within an occupation.
Compressor
A device for mechanically increasing the pressure of a refrigerant vapour.
Condenser
A heat exchanger in which vaporised refrigerant is liquefied by removal of heat
Condensing unit
A combination of one or more compressors, condensers, liquid receivers
(when required) and the regularly furnished accessories.
Containment
The application of service techniques or special equipment designed to
preclude or reduce loss of refrigerant from equipment during installation,
operation, service or disposal of refrigeration and air-conditioning equipment.
Controlled substance
Under the Montreal Protocol, any ozone depleting substance that is subject to
control measures, such as a phase-out requirement.
Destruction
Destruction of ozone depleting substances or their mixtures by approved
destruction plants.
Dew point
Vapour saturation temperature of a refrigerant at the specified pressure; the
temperature at which a vapour refrigerant first begins to condense.
Disposal
Conveying a product to another party, usually for destruction.
Drop-in replacement
The procedure for replacing CFC refrigerants with non-CFC refrigerants in
existing refrigerating, air-conditioning and heat pump plants without doing
any plant modifications. However, drop-in procedures are normally referred to
as retrofitting because plants need minor modifications, such as the change
of lubricant, and the replacement of the expansion device and the desiccant
material.
Emissions
The release of gases or aerosols into the atmosphere over a specified area
and period of time.
Evaporator
A heat exchanger in which liquid refrigerant is vaporized by absorbing heat
from the substance to be cooled.
Expansion device
A device, such as an expansion valve, expansion orifice, turbine or capillary
tube, that is used to control the mass flow of a refrigerant from the highpressure
side to the low-pressure side of a refrigeration system.
Fluorocarbons
Halocarbons containing fluorine atoms, including chlorofluorocarbons,
hydrochlorofluorocarbons, hydrofluorocarbons and perfluorocarbons.
144

Glossary
Fossil fuels
Carbon-based fuels derived from geological (fossil) carbon deposits.
Examples include coal, oil and natural gas.
Fractionation
The change in composition of a refrigerant mixture by e.g. evaporation of the
more volatile component(s) or condensation of the less volatile component(s).
Gauge pressure
The pressure for which the value is equal to the difference between the
absolute pressure and atmospheric pressure.
Global warming potential (GWP)
An index comparing the climate impact of an emission of a greenhouse
gas relative to that of emitting the same amount of carbon dioxide. GWP is
determined as the ratio of the time integrated radiative forcing arising from
a pulse emission of 1 kg of a substance relative to that of 1 kg of carbon
dioxide, over a fixed time horizon.
Greenhouse effect
Greenhouse gases in the atmosphere effectively absorb the thermal infrared
radiation that is emitted by the Earth’s surface, by the atmosphere itself,
and by clouds. The atmosphere emits radiation in all directions, including
downward to the Earth’s surface. Greenhouse gases trap heat within the
surface troposphere system and raise the temperature of the Earth’s surface.
This is called the natural greenhouse effect. An increase in the concentration
of greenhouse gases leads to increased absorption of infrared radiation and
causes a radiative forcing, or energy imbalance, that is compensated for by
an increase in the temperature of the surface-troposphere system. This is the
enhanced greenhouse effect.
Greenhouse gases (GHGs)
The gaseous constituents of the atmosphere, both natural and
anthropogenic, that absorb and emit radiation within the spectrum of the
thermal infrared radiation that is emitted by the Earth’s surface, by the
atmosphere and by clouds. This property causes the greenhouse effect.
The primary greenhouse gases in the Earth’s atmosphere are water vapour,
carbon dioxide, nitrous oxide, methane and ozone. Moreover, there are a
number of entirely anthropogenic greenhouse gases in the atmosphere, such
as the halocarbons and other chlorine- and bromine-containing substances
that are covered by the Montreal Protocol. Some other trace gases, such as
sulphur hexafluoride, hydrofluorocarbons, and perfluorocarbons , are also
greenhouse gases.
Halocarbons
Chemical compounds containing carbon atoms, and one or more atoms
of the halogens chlorine, fluorine, bromine or iodine. Fully halogenated
halocarbons contain only carbon and halogen atoms, whereas partially
halogenated halocarbons also contain hydrogen atoms. Halocarbons
that release chlorine, bromine or iodine into the stratosphere cause ozone
depletion. Halocarbons are also greenhouse gases. Halocarbons include
chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons,
perfluorocarbons and halons.
Halogens
A family of chemical elements with similar chemical properties that includes
fluorine, chlorine, bromine and iodine.
Heat
It is a form of energy that transferred from one place to another owing to a
temperature difference between them. Heat could be transferred from one
form of energy to another.
Heat exchanger
A part of the refrigerating system used for transferring heat across a
boundary, including the condenser, evaporator, and intercoolers.
Hermetic
An airtight sealed system.
Hermetic compressor
A combination of a compressor and electrical motor, both of which are
enclosed in the same housing, with no external shaft or shaft seals, the
electrical motor operating in a mixture of oil and refrigerant vapour.
145

Glossary
High pressure side
The part of a refrigerating system operating at approximately the condenser
or gas cooler pressure.
Hydrocarbons (HCs)
Chemical compounds consisting of one or more carbon atoms surrounded
only by hydrogen atoms.
Hydrochlorofluorocarbons (HCFCs)
Halocarbons containing only hydrogen, chlorine, fluorine and carbon atoms.
Because HCFCs contain chlorine, they contribute to ozone depletion. They
are also greenhouse gases.
Hydrofluorocarbons (HFCs)
Halocarbons containing only carbon, hydrogen and fluorine atoms. Because
HFCs contain no chlorine, bromine or iodine, they do not deplete the ozone
layer. Like other halocarbons they are potent greenhouse gases.
Isolating valve
A valve which prevent flow in either direction when closed.
Joint
A connection made between two parts.
Kyoto Protocol
The Kyoto Protocol to the United Nations Framework Convention on Climate
Change (UNFCCC) was adopted at the Third Session of the Conference
of the Parties (COP) to the UNFCCC in 1997 in Kyoto, Japan. It contains
legally binding commitments, in addition to those included in the UNFCCC.
Countries included in Annex B of the Protocol agreed to reduce their
anthropogenic greenhouse-gas emissions (specifically carbon dioxide,
methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur
hexafluoride) by at least 5% below 1990 levels in the commitment period
2008 to 2012. The Kyoto Protocol entered into force on 16 February 2005.
Latent heat
It is the amount of heat needed to change the phase of a pure substance
where temperature remains constant.
Liquid receiver
A vessel permanently connected to a system by inlet and outlet pipes for
accumulation of liquid refrigerant.
Low pressure side
The part of a refrigerating system operating at approximately the evaporator
pressure.
Machinery room
A completely enclosed room or space, vented by mechanical ventilation and
only accessible to authorized persons, which is intended for the installation
of components of the refrigerating system or of the complete refrigerating
system. Other equipment may also be installed provided it is compatible with
the safety requirements for the refrigerating system.
Maintenance
All kinds of work that may be performed by a maintenance technician,
primarily related to ensuring the continued good operation and working of
refrigeration systems, as well as record-keeping.
Materials safety data sheet (MSDS)
A safety advisory bulletin prepared by chemical producers for a specific
refrigerant or compound.
Maximum allowable pressure
The maximum pressure for which the equipment is designed, as specified by
the manufacturer.
Maximum working pressure
The maximum pressure for which the equipment is designed, as specified by
the manufacturer.
Mobile system
A refrigerating system which is normally in transit during operation.
Montreal Protocol
The Montreal Protocol on Substances that Deplete the Ozone Layer was
adopted in September 1987. Following the discovery of the Antarctic ozone
146

Glossary
hole in late 1985, governments recognized the need for firm measures to
reduce the production and consumption of a number of CFCs (CFC-11,
-12, -113, -114, and -115) and several Halons (1211, 1301, 2402). The
Protocol was designed so that the phase-out schedules could be revised
on the basis of periodic scientific and technological assessments. Following
such assessments, the Protocol was adjusted to accelerate the phaseout
schedules in 1990 (London), 1992 (Copenhagen), 1995 (Vienna), 1997
(Montreal), 1999 (Beijing) and again in 2007 in Montreal.
Multilateral Fund
Part of the financial mechanism under the Montreal Protocol. The Multilateral
Fund was established by a decision of the Second Meeting of the Parties to
the Montreal Protocol (London, June 1990) and began its operation in 1991.
The main objective of the Multilateral Fund is to assist Article 5 parties to the
Montreal Protocol whose annual per capita consumption and production of
ODS is less than 0.3 kg to comply with the control measures of the Protocol.
Non-condensable gases
Gases with very low temperature boiling points, which are not easily
condensed. Nitrogen and oxygen are the most common ones.
Normal boiling point (NBP)
The boiling point of a compound at atmospheric pressure (1.013 bar).
Occupied space
A completely enclosed space which is occupied for a significant period by
people. The occupied space may be accessible to the public (for example
supermarket) or only to trained persons (for example cutting up of meat).
In an occupied space, both parts of a refrigerating system or the complete
refrigerating system may be located/installed.
Open compressor
A compressor having a drive shaft penetrating the refrigerant-tight housing.
Ozone depletion
Accelerated chemical destruction of the stratospheric ozone layer by the
presence of substances produced by human activities.
Ozone depleting potential (ODP)
A relative index indicating the extent to which a chemical product may cause
ozone depletion compared with the depletion caused by R11. Specifically, the
ODP of an ozone depleting substance is defined as the integrated change in
total ozone per unit mass emission of that substance relative to the integrated
change in total ozone per unit mass emission of R11.
Ozone layer
The layer in the stratosphere where the concentration of ozone is greatest.
The layer extends from about 12 to 40 km. This layer is being depleted by
anthropogenic emissions of chlorine and bromine compounds. Every year,
during the Southern Hemisphere spring, a very strong depletion of the
ozone layer takes place over the Antarctic region. This depletion is caused
by anthropogenic chlorine and bromine compounds in combination with the
specific meteorological conditions of that region. This phenomenon is called
the Antarctic ozone hole.
Ozone
The triatomic form of oxygen (O3), which is a gaseous atmospheric
constituent. In the troposphere it is created by photochemical reactions
involving gases occurring naturally and resulting from anthropogenic activities
(‘smog’). Tropospheric ozone acts as a greenhouse gas. In the stratosphere
ozone is created by the interaction between solar ultraviolet radiation
and molecular oxygen (O2). Stratospheric ozone plays a major role in the
stratospheric radiative balance. Its concentration is highest in the ozone
layer.
Ozone depleting substances (ODS)
Substances known to deplete the stratospheric ozone layer. ODS controlled
under the Montreal Protocol and its Amendments are chlorofluorocarbons,
hydrochlorofluorocarbons, halons, methyl bromide, carbon tetrachloride,
methyl chloroform, hydrobromofluorocarbons and bromochloromethane.
Perfluorocarbons (PFCs)
Synthetically produced halocarbons containing only carbon and fluorine
atoms. They are characterized by extreme stability, non-flammability, low
toxicity, zero ozone depleting potential and high global warming potential.
147

Glossary
Phase-out
The ending of all production and consumption of a chemical controlled under
the Montreal Protocol.
Piping
All pipes or tubes (including hoses, bellows, fittings, or flexible pipes) for
interconnecting the various parts of a refrigerating system.
Power
It’s the time rate of which work is done or energy is transferred.
Pressure relief device
A pressure relief valve or bursting disc device designed to relieve excessive
pressure automatically.
Pressure relief valve
A pressure actuated valve held shut by a spring or other means and designed
to relieve excessive pressure automatically by starting to open at a set
pressure and re-closing after the pressure has fallen below the set pressure.
Push-pull method
A method for recovering and recycling refrigerant from a system using a
negative pressure (suction) on one side to pull the old refrigerant out and
pumping recycled refrigerant vapour to the other side to push the old
refrigerant through the system.
Reclaim
Processing used refrigerants to new product specifications. Chemical analysis
of the refrigerant determines that appropriate specifications are met. The
identification of contaminants and required chemical analysis both are specified
in national and international standards for new product specifications.
Reclamation
Reprocessing and upgrading of a recovered controlled substance through
mechanisms such as filtering, drying, distillation and chemical treatment
in order to restore the substance to a specified standard of performance.
Chemical analysis is required to determine that appropriate product
specifications are met. It often involves processing off-site at a central facility.
Recovery
The collection and storage in an external container, of controlled substances
from machinery, equipment, containment vessels, etc., during servicing or
prior to disposal without necessarily testing or processing it in any way.
Recycling
Reducing contaminants in used refrigerants by separating oil, removing noncondensables
and using devices such as filters, driers or filter-driers to reduce
moisture, acidity and particulate matter. The aim of recycling is to reuse the
recovered refrigerant and normally involves recharge back into equipment and
it often occurs on-site.
Refrigerant
A fluid used for heat transfer in a refrigerating system, which absorbs heat at a
low temperature and a low pressure and rejects heat at a higher temperature
and a higher pressure usually involving changes of the state of the fluid.
Refrigerant detector
A sensing device which responds to a pre-set concentration of refrigerant gas
in the environment.
Refrigerating system
A combination of interconnected refrigerant-containing parts constituting one
closed refrigerant circuit in which the refrigerant is circulated for the purpose
of extracting and rejecting heat (i.e. cooling, heating).
Refrigeration
It is the process of lowering the temperature of substance or a space to a
desired temperature based on type of application.
Retrofit
The upgrading or adjustment of equipment so that it can be used under
altered conditions; for example, of refrigeration equipment to be able to use
an alternative refrigerant in place of a CFC, HCFC or HFC.
Saturated vapour pressure
The maximum vapour pressure of a substance at a given temperature when
accumulated over its liquid state in a confined space.
148

Glossary
Sealed system
A refrigerating system in which all refrigerant containing parts are made tight
by welding, brazing or a similar permanent connection; it contains no nonpermanent
connections.
Secondary (or indirect) cooling system
A system employing a fluid which transfers heat from the product or spaces
to be cooled or heated or from another cooling or heating system to the
refrigerating system without compression and expansion of the fluid.
Semi-hermetic compressor
A combination consisting of a compressor and electrical motor, both of which
are enclosed in the same housing, having removable covers for access, but
having no external shaft or shaft seals, the electrical motor operating in a
mixture of oil and refrigerant vapour.
Sensible heat
It is the amount of heat that causes a change in the temperature of substance
without changing its phase. It can be evaluated by means of temperature
reading device.
Servicing
All kinds of work that may be performed by a service technician, from
installation, operations, inspection, repair, retrofitting, redesign and
decommissioning of refrigeration systems to handling, storage, recovery and
recycling of refrigerants, as well as record-keeping.
Shut-off device
A device to shut off the flow of the fluid, e.g. refrigerant, brine.
Soft soldered joint
A joint obtained by joining of metal parts with metallic mixtures or alloys which
melt below 200 °C.
Soldered joint
A joint obtained by the joining of metal parts with metallic mixtures or alloys
which melt at temperatures in general less than 450 °C
Specific heat
The quantity of heat needed to raise a unit mass of substance by 1°C. It is
measured in joules per Kelvin per kilogram.
Strength test pressure
The pressure that is applied to test the strength of a refrigerating system or
any part of it.
Tightness test
The pressurisation of a refrigeration system, or any part of it, in order to test
for its tightness against leaks.
Ton refrigeration (TR)
It’s the common used unit for refrigeration or air-conditioning system capacity.
It is defined as the rate of energy required to melt a ton of ice at 0 oC in 24
hours. 1 ton of refrigeration (TR) = 3.517 kW = 12,000 Btu/h.
Total equivalent warming impact (TEWI)
A measure of the overall global-warming impact of equipment based on
the total related emissions of greenhouse gases during the lifetime of the
equipment, including its manufacture and the disposal of the operating
fluids and hardware at the end-of-life. TEWI takes into account both direct
emissions, and energy related emissions produced through the energy
consumed in operating the equipment. TEWI is measured in units of mass of
CO2 equivalent.
Transcritical cycle
A refrigerating cycle whose compressor discharges refrigerant at a pressure
above the critical point.
Transitional substance
Under the Montreal Protocol, a chemical whose use is permitted as a
replacement for ozone depleting substances, but only temporarily because
the substance’s ozone depleting potential is non-zero.
Ultraviolet radiation (UV)
Radiation from the Sun with wavelengths between visible light and X-rays.
149

Glossary
UV-B (280–320 nm), one of three bands of UV radiation, is harmful to life on
the Earth’s surface and is mostly absorbed by the ozone layer.
United Nations Environment Programme (UNEP)
Established in 1972, UNEP is the specialised agency of the United Nations for
environmental protection.
Venting
A service practice where the refrigerant is allowed to escape into the
atmosphere, and is usually done as a short-cut instead of recovery.
Vapour compression refrigeration cycle - vapour compression technology
The most widely used refrigeration cycle. In this cycle refrigerant is vaporized
and condensed alternately and is compressed in the vapour phase. Basic
components are: compressor, condenser, expansion device, and evaporator.
Welded joint
A joint obtained by the joining of metal parts in the plastic or molten state.
Zeotrope
A refrigerant blend consisting of two or more substances of different volatilities
that appreciably changes in composition or temperature as it evaporates
(boils) or condenses (liquefies) at a given pressure. A zeotropic refrigerant
blend assigned an R4xx series number designation in ISO 817.
150

Acknowledgements
Acknowledgements
ISBN: 978-92-807-2911-5
UNEP Job Number: DTI/1040/PA
This publication was produced by the United Nations Environment
Programme Division of Technology, Industry and Economics (UNEP
DTIE), OzonAction Branch, as part of UNEP’s work programme
as an Implementing Agency of the Multilateral Fund for the
Implementation of the Montreal Protocol.
The project was managed by the following team in the OzonAction Branch
• Mr. Rajendra Shende Head
• Ms. Anne Fenner Information Manager
• Mr. Halvart Koeppen Regional Network Coordinator, Europe and Central Asia
• Ms. Barbara Huber Programme Assistant
• Ms. Ursulet Mugure Kibe Documentation Assistant
This publication was written by
• Dr. Roberto de Aguiar Peixoto Centro Universitario, Instituto Mauá de
Tecnologia (MAUA), Brazil
Peer review was provided by
• Dr. Daniel Colbourne Re-phridge, United Kingdom
Additional review and input was provided by
• Prof. Radhey Agarwal Indian Institute of Technology, India
• Mr. Yerzhan Aisabayev Programme Officer, OzonAction Compliance
Assistance Programme (CAP), UNEP ROLAC, Panama
• Dr. Ezra Clark Programme Officer, OzonAction Branch, UNEP DTIE, France
• Mr. James S. Curlin Interim Network and Policy Manager, OzonAction Branch,
UNEP DTIE, France
• Mr. Ayman El Talouny Programme Officer, OzonAction CAP, UNEP ROWA,
Bahrain
• Mr. Etienne Gonin Project Coordinating Consultant, EC JumpStart Project,
OzonAction Branch, UNEP DTIE, France
• Mr Yamar Guisse Programme Officer, OzonAction CAP, UNEP ROA, Kenya
• Mr Shaofeng Hu Programme Officer, OzonAction CAP, UNEP ROAP, Thailand
• Mr. Marco Pinzon Programme Officer, OzonAction CAP, UNEP ROLAC,
Panama City
• Mr. Saiful Ridwan Information Technology Specialist, OzonAction CAP, UNEP
DTIE, France
Editing
• Mr. Wayne Talbot consultant, United Kingdom
Design and e-book platform
• Steve Button, Brigitte Bousquet DesignAnnexe
• Marcella Cucco Illustrations
UNEP DTIE wishes to thank all of above contributors for helping to
make this manual possible.

About the UNEP DTIE
About the UNEP Division of Technology,
Industry and Economics
The UNEP Division of Technology, Industry and Economics (DTIE)
helps governments, local authorities and decision-makers in
business and industry to develop and implement policies and
practices focusing on sustainable development.
The Division works to promote:
• sustainable consumption and production,
• the efficient use of renewable energy,
• adequate management of chemicals,
• the integration of environmental costs in development policies.
The Office of the Director, located in Paris, coordinates activities through:
• The International Environmental Technology Centre - IETC (Osaka, Shiga),
which implements integrated waste, water and disaster management
programmes, focusing in particular on Asia.
• Sustainable Consumption and Production (Paris), which promotes
sustainable consumption and production patterns as a contribution to
human development through global markets.
• Chemicals (Geneva), which catalyzes global actions to bring about the
sound management of chemicals and the improvement of chemical
safety worldwide.
• Energy (Paris and Nairobi), which fosters energy and transport policies
for sustainable development and encourages investment in renewable
energy and energy efficiency.
• OzonAction (Paris), which supports the phase-out of ozone depleting
substances in developing countries and countries with economies in
transition to ensure implementation of the Montreal Protocol.
• Economics and Trade (Geneva), which helps countries to integrate
environmental considerations into economic and trade policies, and
works with the finance sector to incorporate sustainable development
policies.
UNEP DTIE activities focus on raising awareness, improving the transfer
of knowledge and information, fostering technological cooperation and
partnerships, and implementing international conventions and agreements.
For more information see 4 www.unep.fr

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